GIFT   OF 
MICHAEL  REESE 


HEATING  AND  VENTILATING 
BUILDINGS.' 


A   MANUAL  FOR  -HEATING  ENGINEERS  AND 
ARCHITECTS. 


BY 


ROLLA  C.  CARPENTER,  M.S.,  C.E.,  M.M.E., 

• 

PROFESSOR  EXPERIMENTAL  ENGINEERING,  CORNELL  UNIVERSITY. 

fast  President   American   Society   Heating:  and   Ventilating   Engineers; 

Member   American    Society    Mechanical   Engineers. 


THIRD   EDITION,    REVISED. 
FIRST  THOUSAND, 


NEW  YORK: 

JOHN    WILEY   &   SONS. 

LONDON:    CHAPMAN  &  HALL    LIMITED. 

1898 


*• 


Copyright,  189^, 

BY 

ROLLA  C.  CARPENTER 


2% 


fchAUNWORTH,    MUNN    A.    BARBER,    PRINTERS   AND    BOOKBINDERS,    NEW    YORK. 


PREFACE. 


THE  subject  of  heating  and  ventilating  buildings  relates  to 
a  branch  of  engineering  devoted  to  a -practical  application  of 
the  general  physical  laws  of  heat  to  the  construction  of  heating 
and  ventilating  apparatus.  A  general  discussion  of  this  subject 
was  given  in  treatises  by  Thomas  Tredgold,  in  1836,  and  by 
Charles  Hood  in  1855,  in  England,  and  by  E.  Peclet  in  1850, 
in  France,  in  which  the  condition  of  the  art  of  heating  and 
ventilating  as  it  existed  at  that  time  was  described.  Since 
those  early  periods  no  treatise  has  been  produced  relating  to 
the  general  principles  and  methods  of  construction  in  vogue, 
although  many  excellent  works  have  been  written  relating  to 
special  systems  or  methods  of  heating,  and  one  very  complete 
and  full  treatise  on  ventilation  has  been  published,  to  which 
reference  is  made  in  various  places  in  the  work. 

The  object  of  the  present  book  is  to  present  to  the  reader 
in  as  concise  a  form  as  possible  a  general  idea  of  the  principles 
which  apply,  and  of  the  methods  of  construction  which  are  in 
use  at  the  present  time  in  various  systems  of  heating  and 
ventilating.  In  writing  the  book  the  aim  has  been  to  present 
first  the  general  principles  which  are  well  established,  and  later 
the  methods  of  application  to  erection  of  systems  of  heating 
and  ventilating.  It  has  been  the  desire  to  render  the  reader 
familiar  with  general  methods  and  important  details  of  con- 
struction, also  with  methods  of  designing  and  estimating  costs 
of  apparatus.  A  full  description  of  the  various  systems  in 
use  at  the  present  time  is  given  so  that  the  reader  may  obtain 
an  intelligent  idea  of  the  relative  merits  of  different  methods 
and  the  classes  of  buildings  to  which  each  is  best  adapted. 

In  preparing  the  present  book,  which  is  an  elementary 
treatise  on  the  subject,  the  writer  has  endeavored  to  present  in 
as  clear  and  concise  a  manner  as  possible,  first,  a  statement  of 


IV  PREFA  CE. 

the  general  principles  and  laws  of  pure  science  which  apply  ; 
second,  a  collection  of  important  tests  which  give  data  and 
figures  showing  the  relation  of  theoretical  principles  to  prac- 
tical construction  ;  third,  a  description  of  the  various  practical 
methods  which  are  in  use  in  heating  and  ventilating  buildings ; 
fourth,  a  description  of  the  methods  of  designing  various  sys- 
tems of  heating  and  ventilating ;  fifth,  a  collection  of  tables 
which  will  be  useful  in  the  practical  application  of  the  princi- 
ples stated. 

The  writer  has  endeavored  to  arrange  the  matter  so  that  it 
can  be  understood  by  any  person  possessing  a  practical  knowl- 
edge of  English  and  arithmetic.  Algebraic  demonstrations, 
when  introduced,  are  printed  in  smaller  type,  and  any  con- 
clusion deduced  is  stated  in  the  form  of  a  rule  or  general 
principle.  Many  valuable  suggestions  and  much  material  aid 
have  been  given  by  J.  J.  Blackmore,  J.  G.  Dudley,  and  W.  S. 
Higgins,  members  of  the  Committee  of  Publication  of  the 
National  Association  of  Manufacturers  of  Heating  Apparatus, 
in  adapting  the  book  for  practical  use. 

It  has  been  the  desire  of  the  writer  to  arrange  the  work  in  a 
scientific  manner,  and  to  give  no  methods  or  rules  of  practice 
which  were  not  based  on  the  results  of  good,  sound  reasoning, 
modified  by  such  coefficients  as  have  been  obtained  by  actual 
tests  or  experience.  In  the  case  of  most  systems  of  heating 
this  has  been  possible,  and  it  is  believed  in  this  respect  that 
the  book  will  be  quite  different  from  anything  which  has  pre- 
ceded it. 

A  great  part  of  the. material  employed  in  writing  the  book 
has  been  used  in  a  course  of  lectures  on  the  subject  of  heating 
to  the  students  in  architecture  in  Cornell  University,  and  one 
of  the  objects  in  preparing  the  work  was  to  make  it  useful  to 
the  architect  as  giving  a  statement  of  principles  and  methods 
of  practice  applying  to  this  branch  of  his  profession.  Professor 
Charles  Babcock  and  C.  F.  Osborne  of  the  Department  of 
Architecture,  Cornell  University,  have  given  material  aid  and 
service  by  suggesting  the  nature  of  the  information  needed  in 
connection  with  building  design. 

The  book  generally  presents  such  information  as  the  writer 
has  found  in  an  extensive  practice  in  the  erection  and  opera- 


PREFA  CE.  V 

tion  of  heating  apparatus  to  be  that  which  is  required  by  con- 
tractors and  by  mechanics  who  have  charge  of  erection  of 
plants.  The  limited  size  of  the  book  does  not  permit  any 
extensive  illustration  of  plants  actually  constructed,  but  a  few 
examples  are  presented,  selected  from  work  done  by  our  most 
noted  engineers  in  this  line. 

For  the  literary  part  of  the  work  obligation  is  due  to  nearly 
every  writer  who  has  preceded  ;  in  nearly  every  case  special 
credit  has  been  given  ;  but  in  the  back  part  of  the  book  will  be 
found  a  complete  list  of  references.  The  writer  has  had  the 
cordial  assistance  of  many  noted  heating  engineers,  many 
manufacturers  of  heating  apparatus,  and  all  the  publishers  of 
current  literature  devoted  to  this  subject. 

The  principal  portion  ojf  the  practical  part  of  the  book  is 
devoted  to  construction  of  gravity  heating  systems  with  steam 
and  hot  water,  but  systems  of  heating  with  hot  air,  with  or 
without  a  blower,  with  exhaust  steam  and  with  electricity,  are 
considered,  and  practical  directions  for  construction  are  given. 
The  general  character  of  the  contents  will  be  best  seen  by  con- 
sulting the  appended  table. 

ITHACA,  N.  Y.,  October  i,  1895 


TABLE  OF  CONTENTS. 


CHAPTER  I. 

NATURE   AND   PROPERTIES   OF   HEAT. 

TICLE  PAGP 

1.  Demand  for  Artificial  Heat i 

2.  Magnitude  of  the   Industry  of  Manufacturing  and   Installing 

Heating  Apparatus i 

3.  Nature  of  Heat 2 

4.  Measure  of  Heat — Heat-unit 4 

5.  Relation  to  Mechanical  and  to  Electrical  Units 4 

6.  Temperature — Absolute  Zero 6 

7.  Thermometer  Scales 7 

8.  Special  Forms  of  Thermometers 9 

9.  Pyrometers  and  Thermometers  for  High  Temperatures 11 

Maxima  and  Minima  Thermometers 12 

Use  of  Thermometers 13 

Specific  Heat 14 

Latent  Heat 15 

Radiation 15 

Reflection  and  Transmission  of  Radiant  Heat 16 

Diffusion  of  Heat 17 

Conduction  of  Heat ....    17 

xl8.  Convection,  or  Heating  by  Contact 19 

19.  Systems  of  Warming 20 


CHAPTER  II. 

PRINCIPLES   OF   VENTILATION. 

20.  Relation  of  Ventilation  to  Heating 21 

21.  Composition  and  Pressure  of  the  Atmosphere 21 

22.  Diffusion  of  Gases  24 

23.  Oxygen 24 

24.  Carbonic  Acid  or  Carbon  Dioxide,  CO2,  and  Carbonic  Oxide. 

CO.... ...     2 


vi ii  ±ABLE  OF  CONTENTS 

ARTICLE  TA36. 

25.  Nitrogen — Argon 27 

26.  Analysis  of  Air 27 

27.  Determination  of  Humidity  of  the  Air 29 

28.  Amount  of  Air  Required  for  Ventilation 31 

29.  Influence  of  the  Size  of  the  Room  on  Ventilation 34 

30.  Force  for  Moving  the  Air 35 

31.  Measurements  of  the  Velocity  of  Air 37 

32.  The  Flow  of  Air  and  Gases 40 

33.  The  Effect  of  Heat  in  Producing  Motion  of  Air 43 

34.  The  Inlet  for  Air 44 

35.  The  Outlet  for  Air 48 

36.  Ventilation-flues 49 

37.  Summary  of  Problems  of  Ventilation 50 

38.  Dimensions  of  Registers  and  Flues , 52 


CHAPTER  III. 

AMOUNT   OF   HEAT   REQUIRED    FOR   WARMING. 

39.  Loss  of  Heat  from  Buildings 54 

40.  Loss  of  Heat  from  Windows 54 

41.  Loss  of  Heat  from  Walls  of  Buildings 55 

42.  Heat  Required  for  Purposes  of  Ventilation — Total  Heat  Re- 

quired      59 

CHAPTER  IV. 

HEAT   GIVEN    OFF    FROM    RADIATING   SURFACES. 

43.  The  Heat  Supplied  by  Radiating  Surfaces 60 

44.  Heat  Emitted  by  Radiation 61 

45.  Heat  Removed  by  Convection  (Indirect  Heating) 63 

46.  Total  Heat  Emitted 64 

47.  Material  of  Radiators 67 

48.  Methods  of  Testing  Radiators 69 

49.  Measurement  of  Radiating  Surface... 73 

50.  Effect  of  Painting  Radiating  Surfaces 74 

51.  Results  of  Tests  of  Radiating  Surface. r 75 

52.  Tests  of  Indirect  Heating  Surfaces 79 

53.  Conclusions  from  Radiator  Tests 83 

54.  Probable  Efficiency  of  Indirect  Radiators 84 

55.  Temperature  Produced  in  a  Room  by  a  given  Amount  of  Sur- 

face when  Outside  Temperature  is  High 84 


TABLE   OF  CONTENTS.  IX 


CHAPTER  V. 

PIPE  AND   FITTINGS    USED   IN   STEAM   AND   HOT-WATER   HEATING. 

\RTICLE  PAGE 

56.  General  Remarks 87 

57.  Cast-iron  Pipes  and  Fittings 87 

58.  Wrought-iron  Pipe 89 

59.  Pipe  Fittings 92 

60.  Valves  and  Cocks 98 

61.  Air-valves 102 

62.  Expansion  Joints 105 


CHAPTER  VI. 

RADIATORS   AND    HEATING   SURFACES. 

63.  Introduction 107 

64.  Radiating  Surface  of  Pipe 107 

65.  Vertical  Pipe  Steam  Radiators 109 

66.  Cast-iron  Steam  Radiator 1 10 

67.  Hot-water  Radiator 112 

68.  Direct  Indirect  Radiator 116 

69.  Indirect  Radiators 1 16 

70.  Proportion  of  Parts  of  a  Radiator 119 


CHAPTER  VII. 

STEAM-HEATING   BOILERS    AND    HOT-WATER   HEATERS. 

71.  General  Properties  of  Steam — Explanation  of  Steam  Tables...  120 

General  Requisites  of  Steam  Boilers 121 

73.  Boiler  Horse-power 122 

74.  Relative  Proportions  of  Heating  to  Grate  Surface 123 

75.  Water  Surface  in  Boiler — Steam  and  Water  Space .  126 

76.  Requisites  for  Perfect  Steam-boiler 127 

77.  Classification  of  Boilers 1 28 

78.  Horizontal  Tubular  Boiler 130 

79.  Locomotive  and  Marine  Boilers 131 

79^7. Vertical  Boilers 132 

8p.  Water-tube  Boilers 133 

X8i.  Hot-water  Heaters 133 

82.  Classes  of  Heating-boilers  and  Heaters 1 36 

83.  Heating-boilers  with  Magazines 141 

84.  Heating-boilers  for  Soft  Coal 142 


TABLE   OF  CONTENTS. 


CHAPTER  VIII. 

SETTINGS   AND    APPLIANCES,    METHODS   OF   OPERATING. 

.ARTICLE  PAGE 

85.  Brick  Settings  for  Boilers 143 

86.  Setting  of  Heating-boilers 147 

87.  The  Safety-valve , 149 

88.  Appliances  for  Showing  the  Level  of  the  Water  in  Boiler 152 

89.  Methods  of  Measuring  Pressure ...  153 

90.  Thermometers 1 56 

91 .  Damper  Regulators 1 56 

92.  Blow-off  Cocks  or  Valves 157 

93.  Expansion  Tank 158 

94.  Form  of  Chimneys ibo 

95.  Size  of  Chimneys 161 

96.  Chimney-tops 1 62 

97.  Grates 163 

98.  Traps 1 64 

99.  Return  Traps 1 67 

-loo.  General  Directions  for  the  Care  of  Steam-heating  Boilers 169 

101.  Care  of  Hot-water  Heaters 171 

J02.  Boiler  Explosions 171 

103.  Explosions  of  Hot-water  Heaters 176 

104.  Prevention  of  Boiler  Explosions 176 

CHAPTER  IX. 

VARIOUS  SYSTEMS  OF  PIPING. 

105.  Systems  Employed  in  Steam-heating 176 

106.  Definitions  of  Terms  Used 176 

107.  Systems  of  Piping 180 

108.  Systems  of  Piping  Used  in  Hot- water  Heating 185 

109.  Combination  Systems  of  Heating 1 88 

1 10.  Pipe  Connections,  Steam-heating  Systems ., 191 

in.  Pipe  Connections,  Hot-water  Heating  Systems 193 

112.  Position  of  Valves  in  Pipes 195 

113.  Piping  for  Indirect  Heaters 196 

114.  Comparisons  of  Pipe  Systems 1 97 

115.  Systems  9f  Piping  where  Steam  does  not  return  to  the  Boiler.  197 

116.  Protection  of  Main  Pipe  from  Loss  of  Heat 198 

CHAPTER  X. 

DESIGN  OF  STEAM  AND  HOT-WATER  SYSTEMS. 

117.  General  Principles „ .  201 

118.  Amount  of  Heat  and  Radiating  Surface  Required  for  Warm- 

ing   202 


TABLE   OF  CONTENTS.  XI 

ARTICLE  PAGE 

1 19.  The  Amount  of  Surface  Required  for  Indirect  Heating 209 

^  f2O.  Summary  of    Approximate   Rules    for   Estimating   Radiating 

Surface 215 

21.  Flow  of  Water  and  Steam 217 

22.  Size  of  Pipes  to  Supply  Radiating  Surfaces 222 

23.  Size  of  Return  Pipes,  Steam  Heating 227 

24.  Size  of  Pipes  for  Hot-water  Radiators 228 

25.  Size  of  Ducts  and  Ventilating  Flue  for  Conveying  Air 232 

126.  Dimensions  of  Registers 235 

127.  Summary  of  Various   Methods  of  Computing  Quantities  Re- 

quired for  Heating 236 

1 28.  Heating  of  Greenhouses 236 

129.  Heating  of  Workshops  and  Factories 245 

CHAPTER  XI. 

HEATING  WITH    EXHAUST   STEAM.      NON-GRAVITY   RETURN   SYSTEMS. 

1 30.  General  Remarks 247 

131.  Systems  of  Exhaust  Heating 247 

132.  Proportions  of  Radiating  Surface  and  Main  Pipes  Required 

in  Exhaust  Heating 249 

133.  Systems  of  Exhaust  Heating  with  Less  than  Atmospheric  Pres- 

sure    251 

134.  Combined  High-  and  Low-pressure  Heating  Systems 255 

135.  Pump  Governors -256 

136.  The  Steam  Loop 257 

137.  Reducing  Valves 258 

1 38.  Transmission  of  Steam  Long  Distances 260 


CHAPTER  XII. 

HEATING  WITH  HOT  AIR. 

1 39.  General  Principles 268 

140.  General  Form  of  a  Furnace 270 

141.  Proportions  Required  for  Furnace  Heating 272 

I  142.  Air-supply  for  the  Furnace 275 

143.  Pipes  for  Heated  Air 276 

144.  The  Areas  of  Registers  or  Openings  into  Various  Rooms 278 

145.  Circulating  Systems  of  Hot  Air 280 

146.  Combination  Heaters. 281 

147.  Heating  with  Stoves  and  Fireplaces 281 

148.  General  Directions  for  Operating  a  Furnace. .  .  282 


xii  TABLE   OF  CONTENTS. 

CHAPTER  XIII. 

FORCED-BLAST  SYSTEMS  OF  HEATING  AND  VENTILATING. 

ARTICLE  yAGE 

149.  General  Remarks  ....  ......................................  283 

150.  Form  of  Steam-heated  Surface  ..................  ............  283 

151.  Ducts  or  Flues—  Registers  .......                                                    .  284 

j  52.   Blowers  or  Fans  .....................................  ......  289 

1  53.   Heating  Surface  Required  .....                         ................  291 

1  54.   Size  of  Boiler  Required  ...............                                 ......  292 

155.   Practical  Construction  of  Hot-blast  System  of  Heating  .......  292 

1  56.  Systems  of  Ventilation  without  Heating  .....................  298 

157.  Heating  with  Refrigerating  Machines  ........................  299 

158.  Cooling  of  Rooms  ...........................................  300 


CHAPTER  XIV. 

HEATING    WITH    ELECTRICITY. 

159.  Equivalents  of  Electrical  and  Heat  Energy  ...................  301 

160.  Expense  of  Heating  by  Electricity  ...........................  301 

161.  Formulae  and  General  Considerations  .......................  304 

162.  Construction  of  Electrical  Heaters  ...........................  306 

163.  Connections  for  Electrical  Heaters  ..........................  309 

CHAPTER   XV. 

TEMPERATURE   REGULATORS. 

164.  General  Remarks  ...........................................  310 

165.  Regulators  Acting  by  Change  of  Pressure  ....................  31  1 

166.  Regulators  Operated  by  Direct  Expansion  ...................  315 

167.  Regulators  Operated  with  Motor—  General  Types  .............  316 

168.  Pneumatic  Motor  System  ...................................  318 

169.  Saving  Due  to  Temperature  Regulation  ......................  320 

CHAPTER  XVI. 

SPECIFICATION    PROPOSALS   AND    BUSINESS   SUGGESTIONS. 

170.  General  Business  Methods  ...................................   322 

171.  General  Requirements  ...................................  ...    323 

172.  Form  Proposed  by  the  National  Association  of  Manufacturers 

of  Heating  Apparatus  .................................     326 

173.  Form  of  Uniform  Contract  ...................  .  .............    336 


TABLE   OF  CONTENTS.  Xlll 

ARTICLE  PAGE 

174.  Specifications  for  Plain  Tabular  and  Water-tube  Boilers 340 

175.  Protection  from  Fire — Hot  Air  and  Steam  Heating 344 

1 76.  Duty  of  the  Architect 347 

177.  Methods  of  Estimating  Cost  of  Construction 347 

1 78.  Suggestions  for  Pipe-fitting 348 

APPENDIX. 

LITERATURE  AND  REFERENCES 353 

EXPLANATIONS  OF  TABLES 356 

TABLES  359 

INDEX 401 


A  TREATISE 

ON 

HEATING  AND  VENTILATING   BUILDINGS. 


CHAPTER   I. 

INTRODUCTION. 

NATURE   AND   PROPERTIES   OF   HEAT. 

1.  Demand  for  Artificial  Heat. — The  necessity  for  artifi- 
cial heat  depends  to  a  great  extent  upon  the  climate,  but  to  a 
certain  extent  on  the  customs  or  habits  of  the  people.      In  all 
the  colder  regions  of  the  earth  artificial  heat  is  necessary  for 
the  preservation  of  life,  yet  there  will  be  found  a  great  difference 
in  the  temperature  required  by  people  of  different  nations  or 
races  living  under  the  same  circumstances.     On  the  continent 
of  Europe,.  1 5  degrees  centigrade,  corresponding  to  about  59 
degrees  F.,  is  considered  a  comfortable  temperature  ;  in  America 
it  is  the  general  practice  and  custom   to  maintain   a  temper- 
ature of  70  degrees  in  dwellings,  offices,  stores,  and  most  work- 
shops, and  a  heating  apparatus  is  considered  inadequate  which 
will   not   maintain    this   temperature    under  all  conditions   of 
weather. 

2.  Magnitude  of  the  Industry  of  Manufacturing  and  In- 
stalling Heating  Apparatus. — The  industry  connected  with 
the  manufacture  and    installation  of   the  various  systems  for 
warming  is  a  great  one  and  gives  employment  to  many  thou- 
sand workmen.     The  manufacture  of  heating  apparatus  is  not 
only  of  great  magnitude,  but  it  is  varied  in  its  nature  ;  all  kinds 
of  apparatus  for  heating — as,  for  instance,  the  open  fireplace 
built  at  the  base  of  a  brick  chimney,  the  cast-iron  stove  with 
its  unsightly  piping,  the  furnace  and  appliances  for  warming 


2  HEATING   AND    VENTILATING   BUILDINGS. 

air,  apparatus  for  heating  by  steam  and  also  by  hot  water — can 
be  readily  bought  on  the  market  in  almost  every  form,  from 
that  of  the  simplest  to  that  of  the  most  complicated  design. 

The  exact  amount  of  capital  invested  in  this  industry  could 
not  be  ascertained  by  the  author,  but  in  twenty  cities,  selected 
in  alphabetical  order  from  a  list  of  one  hundred  and  sixty-five 
cities  of  the  United  States  containing  over  twenty  thousand 
inhabitants,  the  total  amount  invested  in  the  business  of  erect- 
ing and  installing  heating  apparatus  as  given  in  the  Census 
Report  by  the  U.  S.  Government  for  1890  was  $12,910,250, 
and  the  yearly  receipts  for  1890  from  this  business  in  the  same 
cities  was  $5,592,148.  The  aggregate  population  of  these 
cities  was  1,573,508  people.  This  would  indicate  an  invest- 
ment of  $8.20  and  a  yearly  expenditure  of  $3.52  for  each 
inhabitant.  Reckoning  on  the  same  basis  for  the  cities  of  the 
United  States  which  contain  over  25,000  inhabitants  each,  we 
should  have  an  invested  capital  of  over  $106,000,000  and  a 
yearly  expenditure  of  over  $46,000,000.  These  numbers  are 
probably  less  than  the  amount  actually  invested,  but  they  serve 
to  give  an  idea  of  the  magnitude  of  the  industry  connected 
with  the  supply  of  apparatus  for  artificial  warming. 

3.  Nature  of  Heat— Before  consideration  of  the  methods 
of  utilizing  heat  in  warming  buildings  a  short  discussion  of  the 
nature  and  scientific  properties  of  heat  seems  necessary. 

Heat  is  recognized  by  a  bodily  sensation,  that  of  feeling, 
by  means  of  which  we  are  able  to  determine  roughly  by  com- 
parison that  one  body  is  warmer  or  colder  than  another.  From 
a  scientific  standpoint  heat  is  a  peculiar  form  of  energy,  similar 
in  many  respects  to  electricity  or  light,  and  is  capable,  under 
favorable  conditions,  of  being  reduced  into  either  of  the  above 
or  into  mechanical  work.  We  shall  have  little  to  do  with  the 
theoretical  discussion  of  its  nature,  but,  as  it  is  well  to  have  a 
distinct  understanding  of  its  various  forms  and  equivalents,  we 
will  consider  briefly  some  of  its  important  properties. 

Heat  was  at  one  time  considered  a  material  substance  which 
might  enter  into  or  depart  from  a  body  by  some  kind  of  con- 
duction, and  the  terms  which  are  in  use  to-day  were  largely 
founded  on  that  early  idea  of  its  material  existence.  The 
theory  that  heat  is  a  form  of  energy  and  is  capable  of 


INTRODUCTION.  3 

transformation  into  work  or  electricity  is  thoroughly  established 
by  fact  and  experiment.  It  probably  produces  a  molecular 
motion  among  the  particles  of  bodies  into  which  it  enters,  the 
rate  of  such  motion  being  proportional  to  the  intensity  of  the 
heat. 

Heat  has  two  qualities  which  correspond  in  a  general  way 
to  intensity  on  the  one  hand  and  quantity  on  the  other.  The 
intensity  of  heat  is  termed  temperature — this  can  be  measured 
by  a  thermometer  ;  but,  except  in  scientific  discussion,  no  name 
has  been  applied  to  designate  the  unit-quantity  of  heat,*  and 
there  is  no  method  of  measuring  it  directly,  although  it  is  of  as 
much  importance  as  temperature. 

It  is  a  fact  which  will  appear  from  later  statements  that  the 
amount  of  heat  contained  in  two  bodies  of  different  kinds,  but 
of  the  same  weight  and  temperature,  may  be  essentially  different. 
A  familiar  analogy  might  perhaps  be  seen  in  the  case  of  the 
dimensions  and  weight  of  men.  The  weight  would  depend  on 
the  general  dimensions,  height,  breadth,  etc.,  and  it  would 
probably  be  the  case  that  two  men  having  equal  heights  would 
have  quite  different  weights.  In  a  similar  manner  the  amount 
of  heat  depends  upon  the  temperature  and  also  upon  the 
property  of  the  body  to  absorb  heat  without  showing  any 
effects  which  may  be  measured  on  a  thermometer.  This  latter 
property  in  itself  depends  upon  the  nature  of  the  body  and 
also  upon  that  peculiar  quality  of  heat  to  which  reference  has 
been  made.  Under  every  condition  heat  must  be  quite  differ- 
ent in  nature  from  temperature. 

Note  that  heat  is  equivalent,  not  to  mechanical  force,  but  to 
mechanical  work.  Work,  defined  scientifically,  is  the  applica- 
tion of  force  in  overcoming  some  resistance;  it  is  the  result  of 
a  force  acting  through  a  certain  distance ;  the  distance  moved 
through  having  as  much  effect  on  the  result  as  the  force  acting. 
The  work  done  is  proportional  to  the  product  of  the  force 
exerted,  multiplied  by  the  space  passed  through.  In  English 
measures  the  unit  of  this  product  is  a  foot-pound,  which  signifies 
one  pound  raised  to  a  height  equal  to  one  foot  ;  it  is  itself  a 
complex  quantity  resembling  heat  in  this  respect.  Heat  can 
be  transformed  into  work. 

*The  term  entropy  is  now  applied  in   scientific   discussions  to  this  property. 


4  HEATING   AND    VENTILATING   BUILDINGS. 

4.  Measure  of  Heat— Heat-unit. — As  explained  heat  can- 
not be  measured    by   the  thermometer;    it  can,  however,  be 
measured  by  the  amount  that  some  standard  is  raised  in  tem- 
perature.    The  standard  adopted  is  water,  and  heat  is  univers- 
ally measured   by  its  power  to  raise  the  temperature  of  a  given 
weight  of  water.    In  English-speaking  countries  the  heat-unit  is 
that  required  to  raise  one  pound  of  water  from  a  temperature  of 
62  to  63  degrees,  and  this  quantity  is  termed  a  British  thermal 
unit ;  this  will  be  referred  to  in  this  work,  by  its  initial  letters 
B.  T.  U.,  or  simply  as  a  heat-unit.     The  amount  of  heat  re- 
quired to  change  the  temperature  of  one  pound  of  water  one 
degree  is  not  the  same  at  all  temperatures ;  the  variation,  how- 
ever, is  slight  and  for  practical  purposes  can  be  entirely  disre- 
garded.    The  unit  of  heat  used  by  the  French  and  Germans, 
and  for  scientific  purposes  generally,  is  called  the  calorie ;  it  is 
equal  to  one   kilogramme  (2.20  pounds)  of  water  raised  one 
degree   centigrade  (1.8  degrees   Fahrenheit)    and   is  equal   to 
3.9672  B.  T.  U.     The  calorie  is  referred  to  water  at  a  temper- 
ature of  15-16°  Centigrade  (60  degrees  Fahrenheit). 

5.  Relation    to    Mechanical  Work    and  to   Electrical 
Units. — The  relation  of  heat  to  mechanical  work  was  accu- 
rately measured  by  Joule  in  1838  by  noting  the  heating  effects 
produced  in  revolving  a  paddle-wheel  immersed  in  water.     The 
wheel  being  revolved  by  a  weight  falling  a  given  distance,  the 
mechanical  work  was  known  ;  this  compared  with  the  rise  in 
temperature  of  the  water  enabled  him  to  determine  that  the 
value  of  one  heat-unit  estimated  from  39°  to  40°  F.  was  equiv- 
alent to  772  foot-pounds.     Later  investigation  has  slightly  in- 
creased this  result,  so  that  when  reduced  to  a  temperature  of 
62  degrees  F.,  and  for  this  latitude,  it  is  6  foot-pounds  greater, 
so  that   at  present   the  work  equivalent  of    one    heat-unit    is 
generally  regarded  as  778  foot-pounds.     This  signifies  that  the 
work  of  raising  I  Ib.  778  feet  is  equivalent  to  the  energy  re- 
quired to  change  the  temperature  of   I  Ib.  of  water,  at  62°  F. 
in  temperature,  I  degree. 

The  equivalent  value  of  heat  and  mechanical  work  is  now 
thoroughly  established,  and  under  favorable  conditions  the  one 
can  always  be  transformed  into  the  other.  As  illustrations  of 
the  transformation  of  heat  into  work  we  have  only  to  consider 


INTROD  UCT1ON.  5 

the  numerous  forms  of  steam-engines,  gas-engines,  and  the  like. 
A  transformation  from  mechanical  work  into  heat  is  shown  in 
the  rise  of  temperature  accompanying  friction  in  the  use  of 
machines  of  all  classes.  The  heat  produced  in  the  perform- 
ance of  any  mechanical  work  is  exactly  equivalent  to  the  work 
accomplished,  778  foot-pounds  of  mechanical  work  being  per- 
formed in  order  to  produce  a  heating  effect  equivalent  to  rais- 
ing i  Ib.  of  water  i°  Fahr. 

The  term  horse-power  has  been  used  as  the  measure  of  the 
amount  of  work.  It  has  been  fixed  as  33,000  foot-pounds  per 
minute.  This  is  equivalent  to  42.42  B.  T.  U.  per  minute,  or 
to  746  watts  in  electrical  measures.  For  the  work  done  in 
one  second  the  above  numbers  should  be  divided  by  60 ;  for 
that  done  in  one  hour  they  should  be  multiplied  by  60.  In  all 
English-speaking  countries  the  capacity  of  engines  and  ma- 
chinery in  general  is  expressed  in  horse-power,  so  that  it  is 
necessary  to  become  familiar  with  this  term  audits  equivalents 
in  heat  and  electrical  units. 

The  electrical  units  are  all  based  on  French  measures,  the  centi- 
metre (0.3937  inch)  being  the  standard  of  length,  the  gramme  (15.432 
grains)  the  standard  of  mass,  and  the  second  the  unit  of  time;  the 
system  being  "generally  denominated  the  C.  G.  S.  system.  In  this 
system  the  unit  of  force,  the  dyne,  is  i  gramme  moved  so  as  to  acquire 
a  velocity  of  one  centimetre  per  second.  As  the  force  of  gravity  in  lati- 
tude of  Paris  is  32.2  feet  =  981  cm.,  the  dyne  is  equal  to  the  weight 
moved,  expressed  in  grammes  divided  by  981,  for  latitude  of  Paris. 

The  unit  of  work  and  of  energy  is  called  an  erg  and  is  equal  to  the 
force  of  one  dyne  acting  through  one  centimetre,  or  to  a  gramme-centi- 
metre divided  by  981. 

One  million  ergs  is  equal  to  0.0738  foot-pound. 

One  watt  is  equal  to  10  million  ergs  per  second,  or  738  foot-pounds 
per  second. 

One  calorie  is  42,000  million  ergs,  one  minor  calorie  42  million  ergs. 

One  B.  T.  U.  is  10,550  million  ergs. 

Expressed  in  work  we  have  the  following  equivalents  : 

One  horse-power  =  746  watts  =550  foot-pounds  per  second 
=  0.707  B.  T.  U.  per  second. 
=  0.1767  calories  per  second 
=  176.7  minor  calories  per  second 
=  7460  millions  of  ergs  per  second. 

(See  full  table  of  equivalents  in  back  of  book.) 


6  HEATING   AND    VENTILATING   BUILDINGS. 

6.  Temperature — Absolute  Zero. — One  of  the  properties 
of  heat  is  called  temperature  ;  this  property  can  be  measured 
by  a  thermometer  and  is  proportional  to  the  intensity  of  the 
heat.  All  our  knowledge  of  heat,  as  obtained  by  the  sensation 
of  feeling,  deals  only  with  the  temperature,  and  the  terms  in 
common  use  by  means  of  which  bodies  are  compared  and 
denominated  hot,  hotter,  hottest,  have  reference,  not  to  the 
heat  actually  in  the  different  bodies,  but  to  the  temperature. 

There  is  always  a  tendency  for  heat  to  flow  through  inter- 
vening mediums  from  a  hotter  to  a  colder  body,  and  there 
is  no  tendency  for  heat  to  flow  from  a  cold  to  a  hot  body, 
although  the  relative  amounts  of  heat  in  the  two  bodies  might 
be  different  from  that  indicated  by  the  thermometer.  Thus,  as 
an  illustration,  a  pound  of  water  requires  about  eight  times  as 
much  heat  to  raise  it  one  degree  in  temperature  as  a  pound  of 
iron,  and  hence  when  equal  weights  of  both  of  these  materials 
are  at  the  same  temperature  the  water  contains  eight  times  as 
much  heat  as  the  iron,  although  in  common  parlance  the  two 
bodies  would  be  equally  hot. 

The  tendency  for  the  hotter  body  to  cool  off  and  give  up 
its  heat  to  surrounding  objects  is  characteristic  of  all  materials, 
and  if  no  other  heat  were  supplied  all  bodies  would  come  sooner 
or  later  to  one  common  temperature.  This  temperature,  when 
finally  reached  by  all  bodies  in  the  universe,  will  represent  the 
ultimate  limit  of  all  cooling  and  almost  the  entire  absence  of 
heat.  It  will  be  near  absolute  zero  for  all  thermometric  scales, 
and  no  greater  cold  will  be  possible  or  even  conceivable.  The 
inter-planetary  space  is  believed  by  many  to  be  very  nearly  at 
this  limit,  at  the  present  time.  Scientific  men  have  made  very 
careful  determinations  to  ascertain  what  such  a  temperature 
must  be,  compared  with  the  ordinary  thermometric  scales. 

A  perfect  gas  which  remains  under  constant  pressure  will 
contract  in  volume  an  amount  directly  proportional  to  the 
change  of  temperature  when  reckoned  from  the  point  of  great- 
est cold,  which  point  is  known  as  the  absolute  zero.  By  experi- 
ment it  is  found  that  when  air  is  at  a  temperature  of  32  degrees 
its  volume  is  reduced  one  part  in  492  each  time  that  the  tem- 
perature is  lowered  one  degree.  From  this  fact  it  has  been 
concluded  that  the  absolute  zero  is  492  degrees  on  the  Fahren- 


IN  TROD.  UCTION. 


heit  scale  or  273  degrees  on  the  Centigrade  scale,  below  the 
freezing-point  of  water.  Strictly  speaking  there  is  no  perfect 
gas,  yet  the  results  obtained  with  different  gases  by  different  ob- 
servers are  so  nearly  in  accord  that  there  is  no  question  but  that 
the  results  as  given  above  are  for  all  practical  purposes  correct. 

7.  Thermometer  Scales. — The  thermometer  is  an  instru- 
ment used  to  measure  temperature.  The  effect  of  heat  is  to 
expand  or  to  increase  the  volume  of  most  bodies.  For  perfect 
gases  the  amount  of  this  expansion  is  strictly  proportional  to 
the  change  of  temperature  ;  for  liquids  and  solids  the  expansion, 
while  not  exactly  proportional  to  the  increase  of  temperature, 
is  very  nearly  proportional  to  it,  and  these  bodies  can  be  used 
for  an  approximate  and  even  a  close  measure  of  difference  of 
temperature.  In  nearly  all  thermometers  the  temperature  is 
measured  by  the  expansion  of  some  body,  mercury,  alcohol,  or 
air  being  commonly  used  as  the  thermometric  substance. 

The  first  thermometer  was  probably  made  by  Galileo  before 
1597.  It  consisted  of  a  glass  bulb  containing  air,  terminated 
below  in  a  long  glass  tube  which  dipped  into  a  vessel 
containing  a  colored  fluid.  The  variations  of  volume 
of  the  enclose'd  air  caused  the  fluid  to  rise  or  fall  in  the 
tube,  the  temperature  being  read  by  an  arbitrary  scale. 
Alcohol  thermometers  were  in  use  as  early  as  1647, 
being  made  by  connecting  a  spherical  bulb  with  a 
long  glass  stem,  on  which  graduations  were  made  by 
beads  of  blue  enamel  placed  in  positions  correspond- 
ing to  one  thousandths  of  the  volume. 

Fahrenheit,  a  German  merchant,  in  1721  was  the 
first  to  make  a  mercurial  thermometer,  and  the  instru- 
ment which  he  designed,  with  certain  modifications,  has 
been  retained  in  use  by  the  English-speaking  people  up 
to  the  present  time.  Fahrenheit  took  as  fixed  points 
the  temperature  of  the  human  body,  which  he  called  24 
degrees,  and  a  mixture  of  salt  and  sal-ammoniac,  which 
he  supposed  the  greatest  cold  possible,  as  zero.  On 
this  scale  the  freezing-point  is  8  degrees.  These 
degrees  were  afterwards  divided  into  quarters,  and 
later  these  subdivisions  themselves,  termed  degrees. 
On  this  modified  scale  the  freezing-point  of  water  becomes  32 


ORDINARY 

FORM      OF 

MERCURI- 
AL THER- 
MOMETER. 


8 


HEATING   AND    VENTILATING   BUILDINGS. 


degrees,  blood-heat  96*  degrees,  and  the  point  of  boiling  water 
at  atmospheric  pressure  212  degrees.  Unscientific  as  this 
thermometer  is,  it  has  been  retained  by  two  of  the  principal 
nations  of  the  world,  the  English  and  the  American  ;  it  is 
awkward  to  use,  it  was  borrowed  from  a  foreign  nation  which 
had  itself  adopted  a  more  scientific  instrument,  and  except  for 
the  fact  that  it  has  been  long  in  use  it  has  not  a  single  feature 
to  recommend  it. 

In  1724  Delisle  introduced  a  scale  in  which  the  boiling- 
point  of  water  was  called  zero  and  the  temperature  of  a  cellar 
in  the  Paris  Observatory  was  called  100  degrees.  This  ther- 
mometer was  used  for  many  years  in  Russia,  but  is  now  obso- 
lete. In  1730  Reaumur  made  alcohol  thermometers  in  which 
the  boiling-point  of  water  was  marked  80  degrees.  This 
thermometer  is  still  in  use  in  Russia. 

Celsius  adopted  a  centesimal  scale  in  1742  on  which  the 
boiling-point  was  marked  zero  and  the  freezing-point  of  water 
100  degrees.  This  instrument  is  not  now  in  use,  although  the 
centigrade  scale  is  often  called  after  Celsius.  The  botanist 
Linnaeus  introduced  the  centigrade  thermometer,  in  which 
the  freezing-point  of  water  is  marked  zero  and  the  boiling- 
point  of  water  100  degrees.  This  themometer  is  now  adopted 
for  ordinary  use  by  the  nations  of  continential  Europe  and  for 
scientific  use  by  every  nation  in  the  world. 

The  relative  values  of  the  degrees  on  the  different  ther- 
mometers used  by  various  nations  are  given  in  the  following 
table  : 

THERMOMETRIC  SCALES. 


Fahren- 
heit. 

Centigrade. 

Reau- 
mur. 

Celsius. 

Degrees  between  freezing  and  boiling.. 
Temperature  at  freezing-point 

I  So 

00 

IOO 

So 

Q 

IOO 
IOO 

Temperature  at  boiling-point     

212 

TOO 

So 

o 

Comparative  length  of  degree 

j 

o/c 

0/A 

Q/- 

Countries  where  used 

5/9 

V/3 

9/4 

5/4 

W  3 

I 

and 
America 

and 
Germany 

*  As  determined  later,  this  should  be  98°. 


INTRODUCTION.  9 

In  all  thermometric  scales  as  given  above,  fixed  points  are 
determined  by  reference  to  the  freezing  and  boiling  points  of 
water,  with  barometer  at  29.92  inches,  and  all  thermometers 
are  constructed  by  marking  these  two  points  and  then  subdi- 
viding into  the  required  number  of  degrees.  The  boiling- 
point  of  water  changes  with  the  atmospheric  pressure  and  with 
the  purity  of  the  water.  The  greater  the  pressure  the  higher 
the  boiling-temperature.  A  table  in  the  Appendix  of  this  book 
shows  the  relation  between  the  barometer*  pressure  and  the 
temperature  of  boiling  water  at  atmospheric  pressure.  Mer- 
cury, alcohol,  liquids  and  solids  generally  do  not  expand 
uniformly  for  each  degree  of  temperature,  or,  in  other  words, 
they  are  not  perfect  thermometric  substances.  The  error, 
however,  is  slight  and  is  of  more  scientific  than  practical  im- 
portance. Any  perfect  gas,  however,  does  expand  uniformly 
and  is  a  perfect  thermometric  substance,  but  gas  varies  in 
volume  with  slight  change  in  barometric  pressure,  and,  while 
of  great  value  as  material  for  a  scientific  thermometer,  is  too 
bulky  and  awkward  for  ordinary  use.  It  is  at  the  present 
time  considered  doubtful  if  there  is  any  perfect  gas  in  exist- 
ence, or  one  which  cannot  be  liquefied  by  intense  cold  or  great 
pressure.  Air,  hydrogen,  and  nitrogen  act  like  perfect  gases  at 
ordinary  temperatures;  the  same  is  true  in  a  slightly  less 
degree  of  oxygen.  Yet  oxygen  is  a  liquid  whose  boiling- 
point  is  119  degrees  centigrade  (182  degrees  Fahrenheit) 
below  zero.  Nitrogen  and  air  are  liquids  boiling  at  a  temper- 
ature of  193  degrees  centigrade  (315  degrees  Fahrenheit) 
below  zero.  Pictet  and  Cailletet  have  reduced  the  temper- 
ature to  200  degrees  C.  below  zero,  finding  air  at  that  tempera- 
ture to  be  a  liquid  as  limpid  as  water  and,  like  water,  having  a 
decided  blue  tint  when  seen  by  transmitted  light. 

8.  Special  Forms  of  Thermometers. — Tr\e  mercurial  ther- 
mometers, as  ordinarily  constructed  (Fig.  i),  consist  of  a  bulb 
of  glass  joined  to  a  capillary  glass  tube  filled  so  as  to  leave  a 
vacuum  in  the  upper  part  of  the  glass  stem,  above  the  mer- 
cury ;  they  cannot  be  used  for  any  temperature  higher  than 
that  of  the  boiling-point  of  mercury,  which  is  about  575°  F. 
More  recently  these  thermometers  have  been  filled  with  nitro- 
gen or  carbonic  dioxide  in  the  upper  part  of  the  glass  stem, 


10 


HEATING   AND    VENTILATING   BUILDINGS. 


which  by  pressure  prevents  the  mercury  boiling.  Thermom- 
eters constructed  in  this  way  can  be  used  safely  in  temperatures 
as  high  as  the  melting-point  of  -ordinary  glass,  say  to  1000°  F. 
Mercurial  thermometers  are  made  in  various  ways ;  the 
cheaper  ones  have  graduations  on  an  attached  frame  of  wood 
or  metal,  Fig.  i,  but  the  more  accurate  and  better  grades 
have  the  graduations  cut  directly  on  to  the  glass  stem, 
Fig.  2.  It  has  been  found  that  the  glass  from  which 
these  thermometers  are  made  changes  volume  slowly  for 
many  months  after  construction,  so  that  it  is  necessary 
to  fill  the  thermometer  with  mercury  a  long  time  before 
graduation.  In  the  better  grade  of  thermometers  the 
graduations  are  obtained  by  comparing  point  by  point 
with  an  accurate  standard  ;  in  the  cheaper  ones  by  sim- 
ply subdividing  into  equal  parts  between  freezing  and 
boiling  points.  At  very  low  temperatures  (—38°  F.)  mer- 
cury solidifies  and  its  rate  of  expansion  changes  ;  alcohol 
or  spirits  of  similar  nature  are  not  so  affected,  and  hence 
are  better  suited  for  use  in  thermometers  for  measuring 

o 

extremely  low  temperatures.  Air  thermometers,  while 
rather  difficult  to  use  and  of  somewhat  clumsy  construc- 
FIG.  2  tion,  are  accurate  through  any  range  of  temperature. 
These  are  made  either  by  confining  the  air  in  a  constant  vol- 
ume and  measuring  the  increase  in  pressure  (Fig.  3),  or  else  by 
maintaining  the  pressure  constant  and 
noting  the  increase  in  volume.  If  the 
volume  be  maintained  constant,  the 
pressure  will  increase  directly  propor- 
tional to  the  increase  in  absolute  tem- 
perature. In  the  air  thermometer  (Fig. 
3)  the  volume  is  kept  constant  and 
the  increase  in  pressure  is  measured 
by  the  rise  of  mercury  in  the  tube 
OC  above  the  line  AB.  That  is,  in 
passing  from  the  freezing  to  the  boil- 
ing point  of  water,  the  barometer  being  FIG.  3.  —  AIR 
at  29.92,  the  pressure  will  increase 
180/492,  as  expressed  on  the  Fahr.  scale,  or  100/273  on  the 
Cen.  scale. 


-t—     •   -r  B 


TER- 


OF   THE 


UNIVERSITY 


IN  TROD  UCTION. 


II 


The  determination  of  temperature  with  the  air  thermometer,  even  if 
the  instrument  is  calibrated  to  read  in  degrees,  needs  a  correction  for 
barometer-reading,  since  the  height  to  which  the  mercury  will  rise  in 
the  tube  will  depend  on  the  pressure  of  the  air.  The  directions  for  using 
the  instrument  would  be:  ist.  Find  the  constant  of  the  instrument  by 
putting  the  bulb  in  melting  ice,  and  dividing  the  absolute  temperature, 
492,  by  the  sum  of  barometer- read  ing  and  reading  of  tube  of  the  ther- 
mometer; 2d.  To  find  any  temperature,  multiply  the  constant  as  found 
above  by  the  sum  of  barometer-reading  and  reading  of  thermometer, 
and  subtract  from  this  product  460°. 

NOTE. — In  using  the  instrument  always  keep  the  mercury  at  or  near 
point  A,  so  as  to  keep  volume  of  air  constant. 

9.  Pyrometers  and  Thermometers  for  High  Temper- 
atures.—  Most  metals  have  rates  of  expansion  which  differ 
sensibly  from  each  other,  and  this  fact  has  been  utilized  in  the 
construction  of  thermometers. 

Metallic  thermometers  are  frequently 
used  for  high  temperatures  and  have  often 
been  called  pyrometers.  If  two  bars  of 
metal  with  unequal  rates  of  expansion  be 
fastened  together  at  one  end  and  heated, 
the  difference  of  extension  of  the  two 
ends  can  be  utilized  in  moving  a  hand 
over  a  dial  graduated  to  show  change  of 
temperature  (Fig.  4).  The  metal  may  also 
be  bent  into  the  form  of  a  helix,  in  which 
case  the  heating  will  tend  to  change  the 
curvature  and  thus  move  a  hand  which 
can  be  used  to  measure  the  temperature. 

A  thermometer  consisting  of  an  iron 
bulb  and  a  dial,  very  much  like  the 
metallic  pyrometer  in  appearance,  is  made 
by  filling  the  bulb  with  ether  or  hydro- 
carbon vapor,  and  constructing  it  on  the 
same  principle  as  gauges  used  to  register 
pressure  on  boilers.  The  vapor  has  a 
temperature  corresponding  to  a  given 
pressure,  so  that  the  dial  can  be  calibrated 
to  read  in  degrees  of  temperature  instead  FlG 

of  pounds  of  pressure.  METALLIC   PYROMETER. 


12 


HEATING   AND    VENTILATING   BUILDINGS. 


These  instruments  are  extremely  convenient  and  answer 
admirably  for  temperatures  not  exceeding  1000°  F. 

Calorimetric  Pyrometers. — The  principle  of  operation  used 
in  determining  specific  heat,  Art.  13,  can,  if  the  specific  heat 
is  known,  be  employed  to  ascertain  the  temperature  of  any 
hot  body. 

Temperature  by  the  Color  of  Incandescent  Bodies  and  by  Melt- 
ing-points.— Pouillet,  as  the  result  of  a  large  number  of  experi- 
ments, concluded  that  all  incandescent  bodies  have  a  definite 
and  fixed  color  corresponding  to  each  temperature. 

This  color  and  temperature  scale  was  given  as  follows : 


Color. 

Temp.   C. 

Temp.    F. 

Faint  red      

Z2Z 

Q7T 

Dark  red  

7OO 

I  2Q^ 

Faint  cherry  

800 

16^2 

Cherry  

QOO 

l6^2 

Bright  cherry  

IOOO 

1932 

Dark  orange  .    .  /  .  .  , 

1160 

1850 

Bright  orange  

I2OO 

2192 

White  heat  

1300 

2372 

Bright  white  

1400 

2552 

Dazzling  white  

1500 

2732 

This  scale  applies  only  to  bodies  that  shine  by  incandescent 
light  and  not  from  actual  combustion.  A  pyrometer  making 
practical  application  of  this  scale  has  been  invented  by  Noel, 
and  consists  of  a  telescope  with  polarizing  attachment  and  a 
scale  so  fixed  as  to  read  the  angle  through  which  a  part  of  the 
instrument  turns  while  a  sudden  transition  of  color  takes  place. 

Temperature  by  the  Melting-points  of  Bodies. — The  melting- 
points  of  bodies  often  provide  an  excellent  means  of  deter- 
mining temperature.  The  temperature  is  obtained  by  using 
metallic  alloys  having  known  melting-points,  it  being  higher 
than  those  which  have  melted,  but  lower  than  those  which 
remain  unmelted.  A  table  of  temperature  of  melting-points 
is  given  in  the  Appendix.  In  Germany  a  carefully  prepared 
set  of  alloys  can  be  purchased  for  temperature  determinations 
in  this  manner. 

10.  Maxima  and  Minima  Thermometers. — The  ordinary 
method  of  making  a  thermometer  for  recording  the  highest 
temperature  is  by  introducing  a  small  piece  of  steel  wire  about 


IN  TROD  UCTION. 


half  an  inch  in  length  and  finer  than  the  bore  of  the  thermom- 
eter into  the  tube  above  the  mercury,  in  a  mercurial  thermom- 
eter. The  thermometer  is  placed  with  its  stem  in  a  horizontal 
position,  and  the  steel  index  is  brought  into  contact  with  the 
extremity  of  the  column  of  mercury.  Now  when  the  heat 
increases  and  the  mercury  expands  the  steel  wire  will  be  thrust 
forward ;  but  when  the  temperature  falls  and  the  mercury 
contracts  the  index  will  be  left 
behind,  showing  the  maximum 
temperature.  For  showing 
minimum  temperature  a  spirit 
thermometer  prepared  in  a 
similar  manner  is  used,  as  the 
spirits  in  contracting  draw  the 
index  with  the  alcohol  because 
of  the  capillary  adhesion  be- 
tween the  alcohol  and  the 
glass ;  but  when  the  alcohol 
expands  it  passes  by  the  index, 
without  displacing  it,  so  that 
its  position  shows  the  lowest 
temperature  to  which  the  in- 
strument has  been  subjected. 

11.  Use  of  Thermom- 
eters.— In  the  use  of  ther- 
mometers for  determining  the 
temperature  of  the  air,  they 
should  be  exposed  to  unob- 
structed circulation  in  a  dry 
place  and  in  the  shade.  Any 


FIG.  5. — STEAM- 
THERMOMETER. 


FIG.  6.— THER- 
MOMETER-CUP. 


drops  of  moisture  on  the  bulb 
of  the  thermometer  tend  to  evaporate  and  lower  the  tem- 
perature. For  determining  the  temperature  of  steam  or  water 
under  pressure  thermometers  are  set  into  a  brass  frame  so  that 
they  will  screw  directly  into  the  liquid  (Fig.  5)  without  per- 
mitting leakage.  In  other  cases  the  thermometer  can  be  in- 
serted into  a  cup  made  as  shown  in  Fig.  6.  Cylinder-oil  or 
mercury  is  put  into  the  cup,  and  the  reading  of  the  thermom- 
eter will  then  indicate  the  temperature  of  the  surrounding 


14  HEATING   AND    VENTILATING   BUILDINGS. 

fluid.  When  the  thermometer  is  inserted  into  a  cup  somt 
time  will  be  required  to  obtain  the  correct  temperature. 
The  temperature  of  steam-pipes  or  hot-water  pipes  cannot 
be  obtained  accurately  by  any  system  of  applying  the 
thermometers  externally  to  the  pipes,  and  in  case  ther- 
mometers are  used  they  should  be  set  deep  info  the  current 
of  flowing  steam  or  water,  not  placed  in  a  pocket  where  air 
can  gather. 

12.  Specific  Heat. — The  capacity  which  bodies  have  of 
absorbing  heat  when  changing  temperature  varies  greatly ; 
for  instance,  the  same  amount  of  heat  which  would  raise  one 
pound  of  water  one  degree  in  temperature  would  raise  about 
8  pounds  of  iron  I  degree  in  temperature  or  would  raise  I 
pound  8  degrees  in  temperature.  The  term  used  to  express 
this  property  of  bodies  is  specific  heat,  which  is  defined  as 
follows:  Specific  heat  is  the  quantity  of  heat  required  to  raise 
the  temperature  of  a  body  one  degree,  expressed  in  percent- 
age of  that  required  to  raise  the  same  amount  of  water  one 
degree,  or  in  other  words  with  water  considered  as  one.  Specific 
heat  can  always  be  found  by  heating  the  body  to  a  given 
temperature,  cooling  it  in  water,  and  noting  the  increase  in 
temperature  of  water.  Thus  if  I  pound  of  iron  in  cooling 
8  degrees  heats  one  pound  of  water  one  degree,  its  specific  heat 
is  -J  =  0.125.  A  table  of  specific  heats  of  the  principal  materials 
is  given  in  the  back  of  the  book,  from  which  it  will  be  seen 
that  the  specific  heat  of  water  is  greater  than  that  of  any 
other  known  substance. 

A  knowledge  of  the  specific  heat  of  various  materials  is  of 
considerable  importance  in  the  design  of  heating  apparatus, 
since  it  indicates  the  capacity  for  absorbing  heat  without  in- 
crease of  temperature.  The  heat  which  is  absorbed  in  raising 
the  temperature  of  a  body  is  all  given  out  when  the  body  cools, 
so  that  although  there  is  a  difference  in  the  amount  absorbed, 
there  is  no  difference  in  the  final  result  due  to  heating  and 
cooling. 

The  total  heat  which  a  body  contains  is  equivalent  to  the 
product  obtained  by  multiplying  difference  of  temperature, 
specific  heat  and  weight.  The  results  will  be  expressed  in 
heat-units  or  in  capacity  of  heating  one  pound  of  water. 


INTRO D  UCTION.  I  5 

The  specific  heat  of  bodies  4n  general  increases  slightly  with 
the  temperature,  the  values  in  the  table  being  true  from  32° 
to  212°. 

13.  Latent  Heat. — When  heat  is  applied  to  any  liquid  the 
temperature  will  rise  until  the  boiling-point  is  reached,  after 
which  heat  will  be  absorbed  ;   but   the  temperature  will   not 
change  until  the  entire  process  of  evaporation  is  complete,  or 
until  the  liquid    is  all   converted    into  vapor.     The   heat  ab- 
sorbed during   evaporation   has   been  termed  latent,  since  it 
does  not   change  the  temperature  and  its   effects  cannot    be 
measured  by  a  thermometer.      In  the  evaporation  of  water 
about  five  and  one-half  times  as  much  heat  is  required  to  evap- 
orate the  water  when  at  212  degrees,  into  steam  at  the  same 
temperature,  as  to  heat  the  water  from  the  freezing  to  the 
boiling   point.       Heat    stored    during   evaporation    is    given 
out  when  the  vapor  condenses,  so  that  there   is  no   loss   or 
gain  in  the  total   operation   of    evaporating  and  condensing. 
A  similar  storage  of  heat  takes  place  when  bodies  pass  from 
the  solid  to  the  liquid  state,  but  in  a  less  degree.     Although 
similar  in  some    respects,    latent   heat   differs  in   nature   from 
specific  heat.     In  both  cases,  heat  not  measured  by  the  ther- 
mometer   is    stored ;  when    the    temperature    is    lowered  the 
stored  heat  is  given  up  in  both  cases:  in  the  first  it  represents 
a    change    in    the    physical  condition,  as    from    a  solid    to  a 
liquid  or  a  liquid  to  a  gas ;  in  the  second  the  condition  remains 
unchanged. 

14.  Radiation.— Heat  passes    from   a  warmer   body  to  a 
colder  by  three  general  methods,  each  of  which  is  of  consider- 
able importance  in  connection  with  the  methods  of  heating. 
These  methods  are  radiation,  conduction,  and  convection.     The 
heat  which  leaves  a  body  by  radiation  travels   directly  and  in 
a  straight  line  until  it  is  intercepted  or  absorbed  by  some  other 
body.     Radiant  heat  obeys  the  same  laws  as  light,  its  amount 
varying  inversely  as  the  square  of  the  distance,  and   with  the 
sine  of  the  angle  of  inclination.     The  amount  of  radiant  heat 
which  is  emitted  or  which  is  absorbed  depends  largely,  if  not 
altogether,  upon  the  character  of  the  surface  of  the  hot  and 
cold  body ;  it  is  found  by  experiment  that   the  power  of  ab- 
sorbing radiant  he.at  is  exactly  the  same  as  that  of  emitting 


1 6  HEATING   AND   VENTILATING   BUILDINGS. 

it.     The    relative   amount   of    heat  emitted    or   absorbed    by 
different  surfaces  is  given  in  the  following  table. 


RELATIVE   EMISSIVE  POWERS  AT  THE  BOILING   TEMPERATURE. 


Lamp-black 100 

White-lead 100 

Paper 98 

Glass 9° 

India  ink 85 

Shellac 7* 


Steel , I? 

Platinum 17 

Polished  brass 7 

Copper 7 

Polished  gold 3 

Polished  silver 3 


Radiant  heat  passes  through  gases  without  affecting  their 
temperature  or  being  absorbed  to  any  appreciable  extent.  It 
is  probably  true  that  a  very  large  body  of  air,  especially  air 

containing  watery  vapor,  does  absorb 
radiant  heat,  for  it  is  known  that  the 
earth's  atmosphere  intercepts  a  sen- 
sible proportion  of  the  heat  radiated 
from  the  sun. 

15.  Reflection  and  Transmis- 
sion of  Radiant  Heat.— Radiant 
heat,  like  light,  may  be  reflected  and 
FIG.  7.— REFLECTION  OF  HEAT.  sent  jn  various  directions  by  materials 
of  various  kinds.  Thus  in  Fig.  7  heat  radiated  from  K  is  re- 
flected to  L,  and  vice  versa.  The  following  table  shows  the 
proportion  of  radiant  heat  which  would  be  reflected  by  various 
substances : 


REFLECTING    POWER. 


Silver-plate 97 

Gold 95 

Brass 93 

Speculum-metal 86 

Tin 85 


Polished  platinum 80 

Steel 83 

Zinc   81 

Iron 77 


Radiant  heat  also  possesses  the  property  of  passing  through 
certain  substances  in  very  much  the  same  manner  that  light 
will  pass  through  glass.  This  property  is  called  diathermancy. 
The  following  table  gives  the  diathermanous  value  of  various 
substances,  the  heat  being  obtained  from  a  lamp.  The  trans- 
mission power  varies  with  the  source  of  heat. 


IN  TROD  UCTION. 


PER    CENT    OF 


HEAT   TRANSMITTED    THROUGH 
SUBSTANCES. 


DIFFERENT 


WHEN    RECEIVED    FROM    AN    ARGAND    LAMP  (DESCHAUD's  PHYSICS). 


SOLIDS. 

Colorless  Glass  \.$>&.mm.  thick. 

Flint-glass from  67  to  64% 

Plate-glass 62  to  59 

Crown-glass  (French) 58 

Crown-glass  (English) 49 

Window-glass 54  to  50 

Colored  Glass  1.85  mm.  thick. 

Deep  violet 53 

Pale  violet 45 

Very  deep  blue. 19 

Deep  blue 33 

Light  blue 42 

Mineral-green. ...    23 

Apple-green 26 

Deep  yellow 40 

Orange 44 

Yellowish  red 53 

Crimson 51 


LIQUIDS  9.21  MM.  THICK. 
Colorless  Liquids. 

DistHled  water n 

Absolute  alcohol 15 

Sulphuric  ether 21 

Sulphide  of  carbon 63 

Spirits  of  turpentine. 31 

Pure  sulphuric  acid   17 

Pure  nitric  acid 15 

Solution  of  sea-salt 12 

Solution  of  alum 12 

Solution  of  sugar 12 

Solution  of  potash 13 

Solution  of  ammonia 15 

Colored  Liquids. 

Nut-oil  (yellow)  . .     31 

Colza-oil  (yellow) 30 

Olive-oil  (greenish  yellow) 30 

Oil-carnations  (yellowish) 26 

Chloride  sulphur  (reddish  brown)..  63 

Pyroligneous  acid  (brown) 12 

White  of  egg  (slightly  yellow) n 


CRYSTALLIZED   BODIES  63.62  MM.  THICK. 


COLORLESS. 

Rock-salt 92$ 

Iceland  spar   12 

Rock-crystal 57 

Brazilian  topaz 54 

Carbonate  of  lead 52 

Borate  of  soda 28 

Sulphate  of  lime 20 

Citric  acid 15 

Rock-alum...  .  12 


COLORED. 

Smoky  quartz  (brown) 57 

Aqua-marina  (light  blue) 29 

Yellow  agate 29 

Green  tourmaline 27 

Sulphate  of  copper  (blue) o 


16.  Diffusion  of  Heat. —  Various  materials  possess  the 
property  of  reflecting  the  radiant  heat  in  such  a  manner  as  to 
diffuse  it  in  all  directions,  instead  of  concentrating  the  heat  in 
any  one  direction.  If  the  heat  were  all  returned,  the  tempera- 
ture of  the  body  would  not  rise,  but  would  remain  constant. 
The  diffusive  power  as  determined  by  Laprovostaye  and 
Desains  was  found  to  be  as  follows  for  the  following  substances, 
the  heat  received  being  100 : 

White-lead 82 

Powdered  silver   76 

Chromate  of  lead . .  .66 


18  HEATING   AND    VENTILATING    BUILDINGS. 

17.  Conduction  of  Heat— When  heat  is  applied  to  one 
end  of  a  bar  of  metal  it  is  propagated  through  the  substance 
of  the  bar,  producing  a  rise  of  temperature  which  gradually 
travels  to  the  remote  portions.  This  transmission  of  heat  is 
called  conduction.  It  differs  from  radiation,  first,  in  being 
gradual  instead  of  instantaneous ;  second,  in  exhibiting  no 
preference  for  travelling  in  straight  lines,  the  propagation 
being  as  rapid  through  a  crooked  as  a  straight  bar.  In  heating 
a  body  the  heat  is  at  first  largely  absorbed  by  the  body  with- 
out changing  its  temperature,  then  for  a  time  it  is  applied  in 
raising  the  temperature ;  the  time  required  for  this  operation 
will  depend  upon  its  specific  heat.  After  a  certain  time  the 
temperature  of  the  body  will  remain  constant,  the  heat  being 
removed  as  rapidly  as  it  reaches  a  given  position,  and  in  this 
case  we  have  an  illustration  of  the  transmission  of  heat  by 
conduction.  The  amount  of  heat  which  passes  is  directly  pro- 
portional to  the  area  of  cross-section,  to  the  difference  of 
temperature  divided  by  the  thickness,  and  to  a  coefficient 
which  depends  upon  the  character  of  the  material.  The  coeffi- 
cient is  the  quantity  of  heat  which  flows,  in  unit  time,  through 
a  cross-section  of  unit  area,  when  the  thickness  of  the  plate  is 
unity  and  the  difference  of  temperature  is  one  degree.* 

The  conducting  power  of  materials  varies  greatly.  The 
metals  are  in  general  good  conductors  of  heat,  but  differ 
greatly  among  themselves.  The  following  table  gives  the 
relative  values  of  the  conducting  powers  for  different  metals : 

RELATIVE  CONDUCTING   POWERS. 


Silver 100 

Copper 77.6 

Gold   53-2 

Brass  33 

Zinc !9-9 

Tin 14.5 


Steel  ..........................  12 

Iron  .........................  17 

Lead  ..........................  8.5 

Platinum  .......................  8.2 

Palladium  .....................  6.3 


Bismuth 


i  .  9 


Rocks  and  earthy  materials  have  very  much  less  power  of 
conducting  heat  than  the  metals.    Table  XIV  in  the  back  part 

*  This  can  be  expressed  in  a  formula  as  follows  : 


in  which  Q  =  quantity  of  heat,  k  =  coefficient,  A  =  area,  x  =  thickness,  /2  — 
r=  difference  of  temperature  on  the  two  sides  of  the  plate. 


IN  TROD  UCTION.  1 9 

of  the  book  gives  the  value  of "  the  coefficient  of  various  mate- 
rials in  terms  of  the  absolute  amount  of  heat  conveyed.  The 
relative  conductive  powers  of  stone  is  about  4  per  cent  of  that 
of  iron  and  f  of  one  per  cent  of  that  of  copper.  The  conduct- 
ing power  of  woods  does  not  differ  greatly  from  that  of 
water,  and  is  about  I  £  per  cent  of  that  of  iron.  The  conduct- 
ing power  of  the  air  and  gases  is  very  small,  and  for  practical 
purposes  may  be  considered  as  zero.  As  compared  with  iron 
the  conducting  power  is  about  as  I  to  3500.  A  knowledge  of 
the  conductive  powers  of  bodies  is  of  very  great  importance 
in  connection  with  the  loss  of  heat  in  buildings  of  various 
classes. 

The  bodily  sensation  of  heat  or  cold  is  affected  to  a  great 
extent  by  the  conducting  power  of  the  material  with  which  the 
body  comes  in  contact.  Thus  if  the  hand  were  placed  upon  a 
metal  plate  at  a  temperature  of  40  degrees,  or  plunged  into 
mercury  of  the  same  temperature,  a  very  marked  sensation  of 
cold  is  experienced.  This  sensation  is  less  intense  with  a  plate 
of  marble  of  the  same  temperature,  and  still  less  with  a  piece 
of  wood.  The  reason  is  that  the  heat  is  more  rapidly  con- 
ducted away  in  the  case  of  the  metals,  and  this  causes  a  more 
marked  sensation  of  cold. 

Where  heat  is  applied  to  one  surface  of  a  metallic  body,  it 
passes  through  the  body  by  conduction  and  is  given  off  on  the 
opposite  side,  usually  to  the  air  or  to  bodies  in  the  surrounding 
room,  by  radiation  and  convection.  It  will  be  found  that  the 
rate  of  conduction  through  the  metallic  body  is  many  times 
greater  than  the  rate  of  passage  of  the  heat  from  the  metallic 
substance.  The  knowledge  of  the  conductive  power  is  of  little 
practical  importance,  as  regards  heating  surface,  because  of  this 
fact,  but  it  is  of  great  value  in  the  selection  of  materials  which 
will  prevent  the  escape  of  heat  from  dwellings.  This  subject 
will  be  taken  up  in  Chapter  III,  and  applications  given  show- 
ing the  loss  of  heat  from  different  constructions  of  building. 

18.  Convection  or  Heating  by  Contact. — When  bodies 
are  in  motion  there  is  more  or  less  rubbing  contact  of  their 
particles  with  each  other  and  against  stationary  objects.  When 
the  particles  rub  against  hot  bodies  they  will  themselves  be- 
come warm  ;  it  is  only  by  such  motion  that  liquids  or  gases 


20  HEATING   AND    VENTILATING   BUILDINGS. 

can  be  heated  any  appreciable  amount.  The  heating  of  the 
air  of  a  room  is  practically.all  accomplished- by  currents,  which 
brings  the  particles  into  contact  with  radiators,  heated  pipes, 
or  even  the  walls  of  a  room.  If  the  air  enters  a  room  at  a 
higher  temperature,  then  by  the  reverse  process  the  heat  is 
given  up  to  the  colder  objects,  and  the  air  is  lowered  in  tem- 
perature. The  heating  of  water  in  steam-boilers  is  largely  due 
to  a  circulation  which  brings  the  particles  of  water  in  direct 
contact  with  highly  heated  surfaces,  so  that  the  heating  in  that 
case  is -accomplished  largely  by  convection. 

19.  Systems  of  Warming.-— Any  general  consideration  of 
a  system  of  warming  must  include,  first,  the -combustion  of 
fuel  which  may  take  place  in  a  fireplace,  stove,  steam  or  hot- 
water  boiler ;  second,  a  system  of  transmission  by  means  of 
which  the  heat  shall  be  conveyed  with  as  little  loss  as  possible 
to  the  position  where  it  can  be  utilized  for  heating  ;  third,  a 
system  of  diffusion  of  heat  so  that  it  shall  be  conveyed  from 
any  reservoir,  radiator,  etc.,  which  is  heated  to  objects,  persons, 
or  to  the  air  of  a  room,. in  the  most  economical  way  possible. 

Jn  case  stoves  are  used  the  heat  is  directly  applied  by 
radiation  and  convection  to  heating  the  objects  and  air  in  the 
room  in  which  the  stove  is  placed.  There  is  in  this  case  no 
special  system  for  the  transmission  of  heat.  In  the  case  of  hot- 
air  heating,  the  air  is  drawn  over  a  heated  surface  and  then 
transmitted  by  pipes  while  at  a  high  temperature  to  the  rooms 
where  heat  is  required.  In  the  case  of  steam-heating,  steam  is 
formed  in  a  boiler,  transmitted  through  pipes  to  radiators 
which  are  placed  either  directly  in  the  room  or  in  passages 
leading  to  the  rooms,  and  the  condensed  steam  is  returned 
either  directly  or  by  means  of  a  pump  to  the  boiler.  In  the 
case  of  hot-water  heating  the  general  system  is  much  the  same 
— water  instead  of  steam  circulates  from  the  heater  to  the 
rooms  where  heat  is  required  and  back  to  the  heater ;  the 
motive  force  which  produces  the  circulation  being  the  differ- 
ence in  weight  between  the  hot  and  cold  water. 


CHAPTER  II. 
PRINCIPLES  OF  VENTILATION. 

20.  Relation    of  Ventilation    to    Heating. — Intimately 
connected  with  the  subject  of  heating  is  the  problem  of  main- 
taining air  of  a  certain  standard  of  purity  in  the  various  build- 
ings occupied.     The  introduction  of  pure  air  can  only  be  done 
properly  in   connection  with  the  system  of  heating,  and  any 
system  of  heating  is  incomplete  and  imperfect  which  does  not 
provide  a  proper  supply  of  air. 

The  general  principles  relating  to  ventilation  are  con- 
sidered in  this  chapter,  but  the  practical  methods  of  securing 
ventilation  are  considered  in  connection  with  systems  of  in- 
direct heating. 

The  subject  of  ventilation  often  receives  very  little  con- 
sideration in  connection  with  the  erection' of  apparatus  for 
heating. 

21.  Composition  and  Pressure  of  the  Atmosphere.— 
Atmospheric  air  is  not  a  simple  substance,  but  consists  of  a 
mechanical  mixture  of  nitrogen   and    oxygen,  together   with 
more  or  less  vapor  of  water,  and  almost  always  a  little  carbonic 
acid  and  a  peculiarly  active  form  of  oxygen,  known  as  ozone. 
The  nitrogen  and  oxygen  are  combined  in  the  ratio  of  79.1  to 
20.9  by  volume,  and  these  proportions  are  generally  the  same 
in  all  parts  of  the  globe,  and  at  all  accessible  elevations  above 
the  earth's  surface. 

The  amount  of  carbonic  acid  in  the  air  varies  in  the  open 
country  from  4  to  6  parts  in  10,000  by  volume.  The  amount 
of  moisture  in  the  atmosphere  sometimes  forms  4  per  cent  of 
its  entire  weight,  and  sometimes  is  less  than  one.tenth  of  one 
per  cent. 

The  weight  of  the  atmosphere  is  measured  by  the  height  in 
inches  at  which  it  will  maintain  a  column  of  mercury  in  an  in- 
strument called  a  barometer.  The  pressure  of  the  atmosphere 
is  less  as  the  distance  from  the  centre  of  the  earth  becomes 

21 


22 


HEATING  AND    VENTILATING   BUILDINGS. 


greater.  For  that  reason  points  of  different  elevation  give 
different  average  readings  of  the  barometer.  The  normal 
reading  of  the  barometer  at  sea-level,  which  corresponds  to  a 
boiling-point  for  pure  water  of  212°  F.,  is  29.905  inches. 

The  weight  of  the  atmosphere,  even  at  the  same  place,  is 
constantly  fluctuating  with  various  conditions  of  the  weather. 
The  variation  in  barometer-reading  from  the  mean  may  be 
1.5  inches  in  either  direction. 

The  fall  of  the  barometer  due  to  different  elevations  from 
the  sea-level  would  be  approximately  as  follows  : 

At    917  feet  the  barometer  sinks  i  inch. 
"    1860     "  "  "     2  inches. 

"    2830     "  "  "     3      " 

"    3830     "  "  "     4      " 

"   4861     "  "     5      " 

The  atmospheric  pressure  has  great  effect  upon  the  boiling- 
temperature  of  water;  thus  pure  water  will  boil  ^.t  the  tem- 
peratures corresponding  to  the  various  barometric  pressures,  as 
shown  in  the  following  table  :* 


Boiling-temperature  F. 

Barometer, 
Inches 

Boiling-temperature  F 

Barometer, 
Inches. 

212 

29.905 

205 

25.990 

211 

29-  33' 

204 

25-465 

210 

28.751 

203 

24.949 

209 

28.180 

2O2 

24.442 

203 

27.618 

201 

23-943 

207 

27.066 

200 

23-453 

206 

26.523 

The  weight  of  a  cubic  foot  of  air  is  inversely  proportional 
to  the  absolute  temperature  ;  if  freed  from  aqueous  vapor  and 
under  a  pressure  of  30  inches  of  mercury,  it  weighs,  according 
to  Regnault,  536.29  grains  or  0.076613  pound,  The  rate  of 

expansion  in  volume  or  decrease  in  density  is  •  >       •  .  for  each 

degree  Fahrenheit,  t  being  temperature  above  32°. 

Table  VIII  in  the  Appendix  gives  the  weights  of  air 
for  different  temperatures.  For  the  temperature  of  60°  air  is 

*  Encyc.  Brit.,  vol.  in.  p.  387. 


PRINCIPLES   OF   VENTILATION.  2$ 

813.67  times  lighter  than  water.  Various  other  units  are 
sometimes  used  to  measure  the  head  or  pressure,  and  for  con- 
venience of  reference  these  equivalents  can  be  arranged  as 
follows : 

30  inches  of  mercury  =  14.7304  Ibs. 

=  407.07  in.  water  ==  33.92  ft,  water 
=  1 1985.4  ft.  air  at  60°  Fahr. 

I  inch  water  =  0.57902  oz. 

Air  contains  more  or  less  impurities  which  are  to  be  found 
only  in  places  where  the  ventilation  is  not  perfect.  These 
impurities  consist  of  carbon  monoxide,  CO,  ammoniacal  com- 
pounds, sulphuretted  hydrogen,  and  sulphuric  and  sulphurous 
and  nitric  and  nitrous  acids.  It  also  contains  some  ozone, 
which  is  a  peculiarly  active  form  of  oxygen,  and  is  believed 
by  many  to  have  an  important  influence  in  the  preservation  of 
the  purity  of  the  atmosphere.  Authorities,  however,  differ  very 
widely  as  to  its  distribution  and  action.  Lately  a  new  con- 
stituent called  argon  has  been  discovered. 

Air  contains  more  or  less  solid  matter  in  the  form  of  minute 
particles  of  dust.  The  dust  particles  are  thought  to  bear  an 
important  part  in  the  propagation  and  distribution  of  the  bac- 
teria of  various  diseases,  and  also  in  the  production  of  storms. 

Air  contains  microbe  organisms,  or  bacteria,  in  greater  or 
less  numbers.  The  number  of  bacteria  may  be  determined 
by  slowly  passing*  a  given  volume  of  the  air  through  a  glass 
tube  coated  inside  with  beef  jelly  ;  the  germs  are  deposited  on 
the  nutrient  jelly,  and  each  becomes  in  a  few  days  the  centre 
of  a  very  visible  colony.  In  outside  air  the  number  of  microbe 
organisms  varies  greatly,  being  often  less  than  one  per  litre  (61 
cubic  inches) ;  in  well-ventilated  rooms  they  vary  from  r  to  20, 
while  in  close  schoolrooms  as  many  as  600  per  litre  have  been 
found.  Carnelley,  Haldane,  and  Anderson  found  in  their 
researches  in  mechanically  ventilated  schoolrooms  an  average 
number  of  \j  microbe  organisms  per  litre.  The  results  of 
stopping  the  mechanical  ventilation  was  to  increase  the  car- 
bonic acid  without  changing  the  number  of  microbe  organisms. 

*  Encyc.  Britannica,  article  "Ventilation." 


24  HEATING   AND    VENTILATING   BUILDINGS. 

22.  Diffusion  of  Gases. — Gases  which  have  no   chemical 
action  on  each  other  will,  regardless  of  weights  or  densities, 
mingle  with  each  other  so  as  to  form  a  perfectly  uniform  mix- 
ture.    This  peculiar  property  is  called  diffusion,  and  is  of  great 
importance  in  connection  with  ventilation,  since  it  indicates 
the  impossibility  of  separating  gases  of  different  densities. 

Liquids  of  different  densities  do  not  make  uniform 
mixtures,  unless  they  have  a  special  affinity  for  each  other  ;  the 
heavier  invariably  settles  to  the  bottom. 

Perfect  diffusion  is  a  process  which  requires  some  time,  so 
that  the  composition  of  samples  from  the  same  room  may  in 
some  instances  be  sensibly  different.  The  time  required  for 
the  diffusion  of  gases  is  inversely  proportional  to  the  density, 
and  directly  proportional  to  the  square  root  of  the  absolute 
temperature.  Diffusion  is  a  molecular .  action,  and  can  be 
calculated  from  the  kinetic  theory  of  gases.  One  computation 
of  this  character  indicates  that  the  time  required  for  the  equal 
diffusion  of  carbonic  acid  throughout  the  atmosphere  was 
2,220,000  years. 

Dr.  Angus  Smith  found  the  following  percentages  of 
oxygen  present  in  the  air,  in  samples  collected  in  various 
places,  which  serve  to  show  the  variation  which  may  exist 
under  different  conditions  :  * 

Seashore  of  Scotland,  on  the  Atlantic 20.99$ 

Top  of  Scottish  hills : 20.98 

Sitting-room,  feeling  close,  but  not  excessively  so. 20.89 

Backs  of  houses  and  closets 20.70 

Under  shafts  in  metal  mines 20.424 

When  candles  go  out 18.50 

When  difficult  to  remain  in  air  many  minutes 17.20 

The  variation  in  amount  of  carbonic  acid  is  equally  great, 
the  quantity  being  as  follows  : 

London  parks 0.0301$  In  workshops 0.3$ 

On  the  Thames o  0343  In  theatres 0.32 

London  streets 0.0380  Cornwall  mines. ....   2.5 

Manchester  fogs 0.0679 

23.  Oxygen, — Oxygen  is  one  of  the  most  important  ele- 
ments of  the  atmosphere,  so  far  as  both  heating  and  ventilation 

*  Encyc.  Brit.,  vol.  xvi.  p.  617  ;  also  vol.  n.  p.  35. 


PRINCIPLES   OF   VENTILATION.  2$ 

is  concerned.  It  is  the  active  element  in  the  chemical  process 
of  combustion,  and  also  of  a  somewhat  similar  physiological 
process  which  takes  place  in. the  respiration  of  human  beings. 
It  exists  in  a  free  state  mixed  with  about  four  parts  of  nitrogen 
in  the  air,  and  is  essential  not  only  for  the  support  of  any  com- 
bustion, but  for  the  support  of  life.  It  is  not  to  be  considered 
as  having  any  properties  as  a  food,  but  is  rather  the  necessary 
element  which  makes  it  possible  to  assimilate  and  utilize  the 
food.  Taken  into  the  lungs  it  acts  upon  the  excess  of  carbon 
of  the  blood,  and  possibly  also  upon  other  ingredients,  forming 
chemical  compounds  which  are  thrown  off  in  the  act  of 
respiration.  The  chemical  action  of  oxygen  with  the  other 
elements  can  generally  be  considered  as  a  sanitary  one.  In 
many  respects  the  process  of  respiration  resembles  that  of 
combustion  ;  for  in  both  cases  oxygen  is  derived  from  the 
air,  carbon  or  other  impurities  are  oxidized,  and  the  products 
of  this  oxidization  are  rejected.  In  both  cases  heat  is  given 
off  as  the  result  of  this  process.  Its  weight  is  sixteen  times 
that  of  hydrogen.  It  is  sometim'es  found  in  a  peculiarly  active 
form  called  ozone. 

24.  Carbonic  Acid  or  Carbon  Dioxide,  CO,,  and  Car- 
bonic Oxide,  CO. — The  first  is  a  product  resulting  from  the 
perfect  combustion  o-f  carbon  ;  it  is  always  found  in  small  quan- 
tities,— 3  to  5  parts  in  10,000  in  the  atmosphere  of  the  country. 

This  gas,  although  very  heavy  as  compared  with  that  of 
pure  air  (22  times  that  of  hydrogen),  will,  if  sufficient  time  be 
given,  mix  uniformly  with  the  air.  It  is  npj^ppjsonous  gas, 
although  in  an  atmosphere  containing  large  quantities  of  car- 
bonic dioxide  a  person  might  die  from  suffocation-  or  for  want 
of  oxygen. 

While  carbonic  dioxide  is  not  of  itself  injurious,  yet  as  it  is 
a  product  of  combustion  and  respiration,  and  is  usually  accom- 
-panied  with  other  injurious  products,  it  is  regarded  as  an  index 
of  the  quality  of  the  air,  and  the  amount  of  it  present  in  the 
air  is  taken  as  the  standard  by  which  we  can  judge  of  the  ven- 
tilation.* In  such  a  case  pure  air,  containing  4  parts  of  car- 


*  }.  S.   Billings,  in  his  work  on  Ventilation  and  Heating,  cites  an  experi- 
ment by  Carneiley  and  Mackie,  showing  that  the   ordinary  theory  of  increase 


26 


HEATING   AND    VENTILATING   BUILDINGS. 


bonic  dioxide  in  io,OOO  would  be  the  standard  of  absolute 
purity.  Authorities  differ  as  to  the  greatest  atnount  of  car- 
bon dioxide  which  might  be  permitted.  It  is  quite  certain  that 
any  unpleasant  sensation  is  not  experienced  until  the  amount  is 
increased  to  10  or  12  parts  in  10,000;  yet  authorities  are  gen- 
erally agreed  that  the  maximum  amount  should  not  exceed  10 
parts  in  10,000,  at  least  for  sleeping-rooms.  The  standard  of 
good  ventilation  usually  adopted  at  present  would  permit 
about  8  parts  in  10,000  in  the  air.  There  has  been  a  tendency 
to  make  the  standard  of  ventilation  higher  and  higher  during 
the  last  few  years,  thus  requiring  the  introduction  of  greater 
quantities  of  air. 

Carbonic  acid  is  continually  increased  by  the  processes  of 
combustion  and  respiration,  yet  for  the  past  thirty  years  the 
amount  in  the  air  has  not  sensibly  changed. 

Plant-growth  and  vegetable  life  assimilate  carbonic  acid 
and  give  off  oxygen.*  There  exists  in  the  air  about  28  tons  of 
carbonic  acid  to  each  acre  of  ground,  yet  an  acre  of  beech- 
forest  annually  absorbs  about  one  ton,  according  to  Chevandier  ; 
and  no  doubt  the  total  vegetation  growing  is  sufficient  to 
absorb  the  excess  due  to  combustion  and  respiration,  so  that 
the  total  does  not  experience  much  change. 

Carbonic  Oxide,  CO.— This  compound  is  not  found  in  the 
air  except  under  unusual  circumstances.  It  is  distinctly  a 
poJspj^,  and  has  a  characteristic  reaction  on  the  blood.  Hem- 
pel,  t  the  German  chemist,  experimented  on  its  poisonous 


of  organic  matter  wiih  mcrease  of  carbon  dioxide  is  a  reasonable  on 
results  of  the  experiment  were  as  follows  : 


The 


Proportion  of 
Organic  Matter. 
Oxygen  required  to 
Oxidize  1,000,000 

Average 
Carbonic  Acid 
in  10.000 
Volumes 

Number  of 
Trials. 

Volumes. 

of  Air. 

o       to     2.5 

2.8 

2O 

2.5  to     9.5 

3  o 

20 

4.5  to     i.o 

3-2 

2O 

7.0  to  15.8 

3-7 

20 

"  How  Crops  Feed,"  by  Johnson,  page  47. 
f  Hempel's  Gas  Analysis.     Macmillan  &  Co. 


PRINCIPLES   OF   VENTILATION.  2/ 

effects  with  a  mouse.  No  symptoms  of  poisoning  were  de- 
tected until  there  were  6  parts  CO  in  io;ooo  of  air,  in  which 
case  after  3  hours'  time  respiration  was  difficult ;  in  another 
case  the  mouse  could  scarcely  breathe  in  47  minutes.  With  12 
parts  in  IO,OOO  the  mouse  showed  symptoms  of  poisoning  in 
7  minutes;  with  29  parts  in  10,000  the  mouse  died  in  convul- 
sions in  about  two  minutes. 

25.  Nitrogen— Argon.— -The  principal  bulk  of  the  earth's 
atmosphere  is  nitrogen,  which  exists  uniformly  diffused  with 
oxygen  and  carbonic   acid.     This  element  is  practically  inert 
in  all  the   processes  of  combustion  or  respiration.     It  is  not 
affected  in  composition  either  by  passing  through  a   furnace 
during  combustion  or  in  passing  through  the  lungs  in  process 
of  respiration.     Its  action  is  to  render  the  oxygen  less  active, 
and  to  absorb  some  part  of  the  heat  produced  by  the  process 
of   oxidation.      It    is   an    element   very   difficult    to    measure 
directly,  as  it  can  be  made  to  enter  into  combination  with  only 
a  few  other  elements,  and    then    under    peculiarly  favorable 
circumstances. 

A  very  small  amount  of  ammonia,  which  is  a  compound  of 
nitrogen  and  hydrogen,  is  found  in  the  atmosphere. 

Argon. — A  constituent  of  the  atmosphere  recently  dis- 
covered, which  amounts  to  about  one  per  cent  of  the  total, 
was  announced  at  the  meeting  of  the  Royal  Society,  January 
31,  1895.  This  element  is  very  soluble  in  water,  and  liquefies 
at  a  temperature  232°  below  zero  F.,  under  a  pressure  of  50.6 
atmospheres.  It  is  even  more  inert  in  action  than  nitrogen, 
and  practically  may  be  considered  the  same. 

26.  Analysis  of  Air. — The  accurate  analysis  of  air  requires 
the  determination  of  aqueous  vapor,  carbon  dioxide,  carbon 
monoxide,  oxygen  and  ozone,  but  for  sanitary  purposes  the 
determination   of  carbon   dioxide  and  water  is  the  most  fre- 
quently  called  for.     For  a  complete  discussion  of  these  various 
methods  the  reader  is  referred  to  Hempel's  Gas  Analysis,  trans- 
lated  by  Dennis   and   published    by  Macmillan   &  Co.     The 
nitrogen   of  the   atmosphere   cannot   be   determined    by  any 
known  method  of  analysis ;   it  is  obtained  by  deducting  the 
sum  of  all  the  other  elements  from  the  total.     The  approxi- 
mate determination   of  the  oxygen   is  done  very  readily  by 


28 


HEATING   AND    VENTILATING   BUILDINGS. 


drawing  a  certain  volume  of  the  air  into  a  measuring-vessel 
and  then  passing  it  over  a  mixture  of  pyrogallic  acid  and 
caustic  potash  ;  the  oxygen  is  absorbed,  reducing  the  volume 
in  amount  proportional  to  the  quantity  of  oxygen.  This  pro- 
cess is,  however,  not  of  extreme  accuracy,  and  for  minute 
quantities  very  much  more  complicated  methods  must  be  re- 
sorted to. 

Method  of  Finding  Carbon  Dioxide  (CO^). — The  amount 
of  this  material  present  in  the  atmosphere  is  so  small  that  the 
most  delicate  methods  are  required  in  order  to  measure  it. 
The  writer  gives  here  the  only  simple  method  which  can  be 
rapidly  applied,  and  which  is  said  to  be  accurate  to  one  part  in 
one  hundred  thousand.  This  system  of  finding  CO2  was  devised 
by  Otto  Pettersson  and  A.  Palmqvist,  two  European  chemists. 
The  instrument  used  for  this  determination  is  shown  in  Fie.  8, 

o 

and  can  be  had  from  any  dealer 
in  physical  apparatus.  It  con- 
sists of  a  measuring-vessel,  A, 
connected  with  a  U-shaped  bu- 
rette B,  from  which  communica- 
tion can  be  made  by  a  small 
stop-cock,  b',  a  manometer,  fg9 
containing  a  graduated  scale 
nearly  horizontal ;  and  two  stop- 
cocks, f  and  g,  by  means  of 
which  communication  can  be 
made  with  the  air.  One  side 
of  this  manometer,/,  is  in  com- 
munication with  the  closed  ves- 
sel C\  the  other  side  can  be 
put  in  communication  with  the 
measuring-vessel  A.  The  burette 
B  contains  a  saturated  solution 
of  caustic  potash  (KOH).  The 
flask  E  contains  mercury,  and 
by  raising  it,  when  the  stop-cock  c  is  open,  the  mercury  will  rise 
in  the  flask  A^  and  the  air  will  be  driven  out.  If  the  flask  E  be 
lowered  the  mercury  will  flow  from  the  measuring-tube,  and 
the  amount  of  air  entering  A  can  be  measured  by  the  gradua- 


FIG.  8  —  PETTKRSSON'S  APPARATUS 
FOR  DETERMINING  CO2  IN  AIR. 


PRINCIPLES   OF   VENTILATION.  29 

tions.  When  the  measuring-tube  A  is  full  of  air,  the  stop-cocks 
c,  b,f,  and  g  being  open,  the  position  of  the  drop  of  liquid  in 
the  horizontal  tube  of  the  manometer  is  accurately  read.  The 
stop-cocks  c,  a,f,  and^are  then  closed,  that  at  £  opened,  and  the 
vessel  E  raised,  driving  the  air  out  of  the  measuring-tube  A 
into  the  absorption  burette  B.  This  operation  of  raising  and 
lowering  the  flask  E  is  repeated  several  times ;  it  is  then 
lowered,  and  the  air  is  drawn  over  into  the  measuring  burette  ; 
the  cock  a  is  then  opened  and  the  vessel  E  manipulated  until 
the  reading  of  the  manometer  on  the  horizontal  scale  agrees 
with  that  in  the  beginning  of  the  test.  The  reading  of  the 
graduated  tube  A  gives  directly  the  amount  of  CO2.  The 
determinations  are  made  with  air  of  ordinary  humidity,  and 
there  is  a  very  slight  correction  due  to  this  fact,  which  is 
not  likely  to  equal,  in  any  case,  one  part  of  CO3  in  one  million 
parts  of  air.* 

27.  Determination  of  Humidity  of  the  Air. — The  hu- 
midity of  the  air  is  determined  by  gradually  cooling  a  body 
and  observing  at  what  temperature  the  vapor  of  the  air  con- 
denses on  the  body  as  dew.  When  dew  is  deposited  the  air 
is  saturated  for  the  given  temperature,  and  if  the  temperature 
of  the  air  be  known,  at  which  dew  will  be  deposited,  and  also 
the  temperature  of  the  air  in  its  normal  condition,  we  can  com- 
pute the  amount  of  moisture  contained  in  the  air.  The  in- 
strument generally  employed  for  this  purpose  consists  of  two 
thermometers,  the  bulb  of  one  of  which  is  exposed  in  its  ordi- 
nary condition  to  the  air ;  the  bulb  of  the  other  is  kept  con- 
stantly wet  by  means  of  a  bit  of  cloth  extending  to  a  vessel 
filled  with  water.  If  the  air  were  saturated  with  moisture 
these  two  thermometers  would  give  the  same  reading,  but  if 
the  air  is  not  saturated  the  readings  will  differ  an  amount  de- 
pending upon  the  humidity.  The  table  following,  and  a  more 
complete  one  in  the  Appendix,  give  the  amount  of  moisture 
expressed  as  percentage  of  saturation  for  different  readings  of 
the  wet  and  dry  bulb  thermometer. 

*  For  approximate  methods  of  determining  the  purity  of  air  see  Appendix 
to  book. 


HEATING   AND    VENTILATING   BUILDINGS. 


MOISTURE  IN  GRAINS   PER    CUBIC 

PER    CENT  OF  SATURATION  FOR  DIF- 

FOOT ABSORBED  BY    SATURATED 

FERENCE  IN  READINGS,  WET  AND 

AIR. 

DRY  BULB  THERMOMETER. 

Temp, 
Air,  degs. 

Grains 
per  cu.  ft. 

Temp. 
Air,  degs. 

Grains 
percu.  ft. 

Difference 
in  Reading. 

.  .     _,  , 

Temp. 
Air,  32°  F. 

Temp. 
Air,  70°  F. 

Temp. 

Air,  95°  F. 

2O 

1-56 

70 

7-94 

r 

o 

100 

100 

100 

32 

2-35 

Bo 

10.73 

I 

96 

97 

97 

40 

3.06 

90 

t4.38 

2 

92 

93 

94 

50 

4.24 

100 

IQ.  12 

3 

88 

QO 

9i 

60 

5.82 

no 

25-5 

5 

81 

84 

86 

7-5 

72 

77 

79 

10 

65 

7i 

73 

15 

52 

59 

62 

20 

41 

49 

53 

The  first  table  gives  the  weight  of  moisture  contained  in 
one  cubic  foot  of  saturated  air;  the  second  shows  the  per- 
centage of  saturation  for  any  difference  in  reading  of  the  wet 
and  dry  bulb  thermometer.  The  weight  of  moisture  is  the 
product  of  the  results.  Thus,  saturated  air  at  70°  F.  contains 
7.94  grdns  per  cubic  foot,  and  if  at  the  same  time  the  differ- 
ence between  the  wet  and  dry  bulb  thermometers  was  10, 
this  air  would  be  71  per  cent  saturated,  and  would  contain 
71  per  cent  of  7.94  grains,  or  5.62  grains.  Since  there  are 
7000  grains  in  one  pound,  this  weight  may,  if  desired,  be  re- 
duced to  pounds. 

Moisture  in  air  can  also  be  determined  approximately,  but 
with  sufficient  accuracy  for  practical  purposes,  by  the  hair 
hygrometer.  This  instrument  is  illustrated  in  Fig.  9.  It  is  con- 
structed by  fastening  a  hair,  from  which  the  oil  has  been  re- 
moved, in  the  top  part  of  a  suitable  frame,  and  winding  the 
lower  part  on  a  cylinder  which  is  free  to  revolve,  and  which 
carries  a  balanced  pointer.  The  hair  increases  or  diminishes 
in  length,  quite  exactly,  in  proportion  to  the  amount  of 
moisture  in  the  air,  and  this  acquired  property  seems  to  be  a 
permanent  one.  A  scale  graduated  by  comparison  with 
determinations  made  with  a  wet  and  dry  bulb  thermometer 
serves  to  show  the  amount  of  moisture  present,  as  a  percentage 
of  saturated  air. 

The  degree  of  moisture  in  the  air  has  an   important   in- 


PRINCIPLES    OF    VENTILATION. 


fluence  on  ventilation.  When^  air  is  saturated  with  moisture 
water  is  deposited  on  all  bodies  which  conduct  heat  readily 
and  have  a  lower  temperature  than  the  air.  On  the  other 
hand,  if  the  air  is  entirely  deprived  of  watery  vapor  it  evap- 
orates moisture  from  the  body,  and  thus  causes  an  unpleasant 
sensation.  It  also  takes  up  a  great  deal  of  heat.  When  the 
air  is  saturated  no  evaporation  can 
take  place  from  the  body.  When 
the  air  is  very  dry,  very  rapid  evap- 
oration will  take  place.  A  mean 
condition  between  these  two  ex- 
tremes is  required  in  every  case. 
The  air  should  be  from  50  to  70 
per  cent  saturated  in  order  to  feel 
pleasant,  and  be  of  the  most  value 
for  ventilating  purposes. 

28.  Amount  of  Air  required 
for  Ventilation.  —  The  amount  of 
air  required  in  order  to  maintain 
the  standard  of  purity  below  a  cer- 
tain given  amount  can  be  very 
readily  determined,  provided  weknow 
the  amount  of  carbon  dioxide  which  is 
given  off  in  the  process  of  respiration. 

It  is  estimated  that  at  each  respiration  of  an  adult  person 
20  cubic  inches  of  air  on  the  average  are  required,  and  that  16 
to  24  respirations  take  place  per  minute  ;  so  that  from  320  to 
480  cubic  inches,  or  about  one  fourth  of  a  cubic  foot,  are 
required  per  minute.*  The  air  ejected  from  the  lungs  is 
delivered  at  a  temperature  from  70  to  90  degrees,  and  very 
nearly  saturated  with  watery  vapor  ;  hence  it  is  about  2. 3  per 
cent  lighter  than  pure  air. 

The  following  table  shows  the  approximate  effect  of 
respiration  on  the  composition  of  air:f 


FIG.  9. — THE  HAIR  HYGROM- 
ETER 


*  This  is  estimated  by  Box  as  Soo  cubic  inches,  but  is  given  by  recent  phys- 
iologists as  above.  See  works  of  Dalton,  Dr.  Carpenter,  Art.  Respiration  in 
Ency.  Brit.,  etc.  This  is  increased  by  violent  exercise,  and  to  make  the  allow- 
ance liberal  576  cubic  inches  or  \  cubic  foot  is  taken  as  the  amount  to  be  supplied. 

f  Ency.  Britannica,  Art.  Respiration. 


HEATING   AND    VENTILATING   BUILDINGS. 


Entering     Respired 
Air.  Gases. 

Oxygen,  per  cent  of  volume 20.26          16 

Nitrogen,  "      "      "         " .      78.00          75 

Watery  vapor"      "         "  1.70  5 

Carbonic  acid  "      "         "        0.04  4 

If  we  take  the  carbon  dioxide  as  an  index  of  the  character 
of  ventilation,  and  consider  that  each  person  uses  one  third 
cubic  foot  of  gas  per  minute,  and  that  the  respired  gas  contains 
400  parts  in  10,000  of  carbonic  acid,  while  the  entering  air  con- 
tains but  4,  we  can  calculate  the  amount  of  air  which  must  be 
provided  to  maintain  any  standard  of  purity  desired.  The 
formula  for  this  operation  would  be  as  follows  :  If  a  =  the 
number  of  parts  of  CO3  in  10,000,  thrown  out  in  respiration  or 
other  impurities  ;  if  b  =  the  cubic  feet  of  air  used  per  minute  ; 
if  n  =  the  standard  of  purity  to  be  preserved,  expressed  as  the 
number  of  units  of  CO2  permissible  in  10,000,  and  C  =  the 
number  of  cubic  feet  of  air  required, — we  shall  have 

C  =  ab/(n  —  4). 

For  the  condition  we  have  just  considered,  for  each  adult 
person  a  =  400,  b  =  -J,  so  that  the  formula  becomes  C=  I33/ 
(n  —  4),  By  taking  n  as  8,  C  =  33,  and  n  as  10,  C  =  22. 

The  following  table  shows  the  amount  of  air  which  must 
be  introduced  for  each  person  in  order  to  maintain  various 
standards  of  purity : 

AMOUNT  OF  AIR  REQUIRED  PER  PERSON  FOR  VARIOUS  STAND- 
ARDS OF  PURITY. 


Standard  Parts  of  CO2  in 
10,000  of  Air  in  the  Room. 

Cubic  Feet  of  Air  required  per  Person. 

Per  Minute. 

Per  Hour. 

5 

133-3 

8  ooo 

6 

67 

4000 

7 

44 

2667 

8 

33 

2000 

9 

27 

16OO 

10 

22 

1333 

ii 

'9 

H5I 

12 

17 

I  OOO 

13 

15 

889 

14 

13 

800 

15 

12 

727 

16 

II 

667 

18 

9-5 

571 

20 

8-3 

500 

PRINCIPLES   OF    VENTILATION.  33 

The  combustion  of  one  cubic  foot  of  gas  per  hour  contam- 
inates about  the  same  amount  of  air  as  one  person,  so  that  an 
allowance,  equivalent  to  that  required  for  four  or  five  people, 
should  be  made  for  each  gas-burner. 

Authorities  differ  greatly  as  to  the  amount  of  air  to  be 
provided  per  person,  but  at  the  present  time  they  seem  well 
united  in  considering  the  admission  of  30  cubic  feet  of  air 
per  minute  for  each  person  as  giving  good  ventilation,  and 
this  amount  is  required  by  law  for  school  buildings  in  Massa- 
chusetts.* 

Some  authorities  insist  that  a  higher  standard  should  be 
required,  but  there  is  little  doubt  that  present  conditions 
would  be  very  much  improved  could  the  above  amount  be 
obtained  in  every  case. 

The  amount  advised  by  various  authorities  has  been  as 
follows :  Parkes  advises  2000  cubic  feet  of  air  per  hour  for 
persons  in  health  and  3000  to  4000  for  sick  persons.  The 
English  Barracks  Improvement  Commissioners  require  that 
the  supply  be  not  less  than  1200  cubic  feet  per  man  per 
hour.  Pettenkofer  recommends  2100  cubic  feet;  and 
Morin  considers  that  the  following  allowances  are  not  too 
high:t 

Hospitals  (ordinary) 2000  to  2400  cubic  feet  per  hour. 

"          (epidemic) 5°°° 

Workshops  (ordinary) 2000 

(unhealthy  trades) 3500 

Prisons 1700 

Theatres 1400101700 

Meeting-halls 1000  ' '  2000 

Schools  (per  child 400"     500 

"       (per  adult) 800  "  1000 


Tredgold  :f  in  1836  considered  4  cubic  feet  of  air  per  minute 
as  good  ventilation  for  healthy  people,  and  6  cubic  feet  per 
minute  for  the  sick  in  hospitals. 


*  Dr.  Billings  states  that  this  amount  could  be  increased  25  to  50  per  cent, 
with  good  results.     Ventilation  and  Heating. 
t  Etudes  sur  la  Ventilation. 
\  Warming  and  Ventilating  Buildings;  third  edition. 


34 


HEATING   AND    VENTILATING   BUILDINGS. 


29.  Influence  of  the  Size  of  the  Room  on  Ventilation.— 
The  purity  of  the  air  of  a  room  depends  to  some  extent  on 
the  proportion  of  its  cubic  capacity  to  the  number  of  inmates. 
This  influence  is  often  overestimated,  and  even  in  a  large 
room  if  no  fresh  air  be  supplied  the  atmosphere  will  quickly 
fall  below  the  standard  of  purity.  It  must  be  considered  that 
no  room  is  hermetically  sealed.  Ventilation  takes  place 
through  every  crack  and  cranny,  and  even  by  diffusion  through 
the  walls  of  the  room.  Such  ventilation  is  generally,  however, 
uncertain  and  inadequate.  Large  rooms  have  the  advantage 
over  small  ones  that  they  act  as  reservoirs  of  air,  and  also  be- 
cause there  is  chance  for  intermittent  ventilation  such  as  occurs 
when  doors  or  windows  are  opened,  and  for  the  casual  ventila- 
tion which  takes  place  through  the  walls  and  around  the  win- 
dows. They  are  also  advantageous,  because  a  larger  volume 
of  air  may  be  introduced  with  less  danger  of  producing  dis- 
agreeable air-currents  or  draughts.  The  following  table,  taken 
in  part  from  article  "  Ventilation,"  Encyc.  Britannica,  gives  a 
general  idea  of  the  cubic  capacity  per  person  usually  allowed 
in  certain  cases,  and  the  time  which  would  be  required  to 
reduce  the  air  inclosed  to  the  lowest  admissible  standard  of 
purity  (12  parts  of  CO2  in  10,000  of  air),  provided  no  fresh  air 
was  admitted. 


Class  of  Building. 

Cubic  Contents. 

Time  required  for 
contaminating 
the  Air. 

Hospitals     

1200  Cl 
1000 

600 
500 
130 
300 
240 

212 

1.    f 

t.  ai 

id  abc 

>ve 

70  m 
59 
35 
29 
8 
18 
14 
13 

in. 

Barracks                               .  . 

Good  secondary  schools  

Workhouse  dormitories     

London  lodging-houses  

It  is  seen  from  the  above  table  that  in  the  ordinary  grade 
of  middle-class  houses  it  would  require  about  one  hour  to 
render  the  air  unfit  for  breathing,  while  for  the  lowest  grade  of 
houses  the  time  required  would  be  only  13  minutes.  It  may 


PRINCIPLES   OF   VENTILATION.  35 

be  said,  however,  respecting  the  cheaper  grade  of  houses,  that 
while  the  amount  of  space  allowed  per  person  is  small,  the 
character  of  construction  is  such  that  air  can  usually  enter  or 
leave  the  room  without  very  great  retardation,  and  conse- 
quently this  table  does  not  fairly  represent  the  character  of 
ventilation  actually  secured. 

Pettenkofer  found  that,  by  diffusion  through  the  walls,  the 
air  of  a  room  in  his  house  containing  2650  cubic  feet  was 
changed  once  every  hour  when  the  difference  of  exterior  and  in- 
terior temperatures  was  34  degrees.  With  the  same  difference 
of  temperature,  but  with  the  addition  of  a  good  fire  in  a  stove, 
the  change  rose  to  3320  cubic  feet  per  hour.  With  all  the 
crevices  and  openings  about  doors  and  windows  pasted  up 
air  tight  the  change  amounted  to  1060  cubic  feet  per  hour  ; 
with  a  difference  of  40  degrees  the  ventilation  through 
the  walls  amounted  to  7  cubic  feet  per  hour  for  each  square 
yard  of  wall  surface.  The  effect  of  diffusion  in  changing 
the  air  of  a  room  should  generally  be  neglected  in  practical 
ventilation,  because  it  is  very  uncertain  in  amount  and 
character. 

30.  Force  for  Moving  the  Air.— No  ventilation  can  be 
secured  unless  provision  is  made  for  (i)  power  for  moving  the 
air,  (2)  passages  and  inlet  for  admitting  the  air,  (3)  passages 
and  outlet  for  escape  of  air.  Air  is  moved  for  ventilating 
purposes  in  two  ways:  first,  by  expansion  due  to  heating; 
and  second,  by  mechanical  means. 

The  effect  of  heat  on  the  air  is  to  increase  its  volume  and 
lessen  its  density  directly  in  proportion  to  the  increase  in 
absolute  temperature.  The  lighter  air  simply  because  of  its 
less  density  (tends  to 'rise, 'and  is  replaced  by  the  colder  air 
below.  The  head  which  induces  the  flow  is  a  column  of  air 
corresponding  in  weight  to  the  difference  in  heights  of  columns 
of  equal  weight  of  cold  and  heated  air.  The  velocity  can  be 
computed,  since  theoretically  it  will  be  equal  to  the  square 
root  of  twice  the  force  of  gravity  into  this  difference  of  height. 
The  result  so  computed  will  apply  only  when  there  is  un- 
restricted openings  at  both  ends.  It  is  scarcely  ever  appli- 
cable to  chimneys,  for  the  reason  that  the  flow  of  air  is  retarded 
by  passing  through  the  fuel. 


36  HEATING   AND    VENTILATING   BUILDINGS. 

The  amount  of  air  which  may  be  made  to  pass  through  a 
ventilating  flue  of  ordinary  construction  and  of  different 
heights  is  given  in  a  table  on  page  45. 

The  available  force  for  moving  the  air  which  is  obtained  by 
heating  is  very  feeble,  and  quite  likely  to  be  overcome  by  the 
wind  or  external  causes.  Thus  to  produce  the  slight  pressure 
equivalent  to  one  tenth  inch  of  water  in  a  flue  50  feet  in 
height  would  require  a  difference  in  temperature  of  50  degrees. 
In  a  flue  of  the  same  height  a  difference  of  temperature  of 
150  degrees  would  produce  the  same  velocity  as  that  caused 
by  a  pressure  of  0.5  inch  of  water.  To  produce  the  same 
velocity  as  that  due  to  a  pressure  sufficient  to  balance  o.i  inch 
of  water  will  require  that  the  product  of  height  of  chimney 
and  difference  of  temperature  should  be  1760. 

It  will  in  general  be  found  that  the  heat  used  for  produc- 
ing velocity,  when  transformed  into  work  in  a  steam-engine  is 
considerably  in  excess  of  that  required  to  produce  draught  by 
mechanical  means.  In  a  rough  way,  an  increase  in  temperature 
of  one  degree  increases  the  head  producing  the  velocity  only 
about  one  part  in  500. 

Ventilation  by  Mechanical  Means  is  performed  either  by  pres- 
sure or  by  suction.  In  the  first  case  the  air  is  increased  in  dens- 
ity and  discharged  by  mechanical  force  into  the  flue,  the  flow 
being  produced  by  an  excess  of  pressure  over  that  of  the  atmos- 
phere, so  that  the  air  tends  to  move  in  the  direction  of  least 
resistance,  which  is  outward  to  the  atmosphere.  In  the  second 
case,  pressure  in  the  flue  is  less  than  that  of  the  atmosphere, 
and  the  velocity  is  produced  by  the  flowing  in  of  the  outside 
air.  By  both  processes  of  mechanical  ventilation  the  air  is 
supposed  to  be  moved  without  change  in  temperature,  and 
the  force  for  moving  it  must  be  sufficient  to  overcome 
effects  of  wind  or  change  of  temperature,  otherwise  the  intro- 
duction of  air  will  not  be  positive  and  certain.  The  velocity 
in  feet  per  second  for  various  differences  of  pressure  is  com- 
puted as  explained  in  Article  32,  and  tables  are  given  on 
pages  42  and  45  for  use  in  computing  the  amount  dis- 
charged per  square  foot  of  the  area  of  the  cross-section  of  the 
flue. 


PRINCIPLES   OF   VENTILATION.  37 

31.  Measurements  of  the  Velocity  of  Air. — The  velocity 
of  air  or  other  gases   is  measured  directly  by  an  instrument 


FIG.  io.—  BIRAM'S  PORTABLE  ANEMOMETER. 

called  an  anemometer,  or  it  is  measured  indirectly  by  differ- 

ence of  pressure.     The  anemometer  which  is  ordinarily  em- 

ployed for  this  purpose  con- 

sists of  a  series  of  flat  vanes 

attached    to    an   axis  and    a 

series   of  dials.     The  revolu- 

tion of   the  axis  causes   mo- 

tion   of    the    hands   in    pro- 

portion   to    the    velocity    of 

the  air.     In  the  forms  shown 

in    Figs,    io  and    n   the  dial 

mechanism  can  be  started  or 

stopped   by  a   trip   arranged 

conveniently  to  the  operator. 

In    some    instances    the  dial 

mechanism  is  operated  by  an 

electric  current,  in  which  case        FIG.  n—  PORTABLE  ANEMOMETER. 


OF  THF 

UNIVERSITY 


HEATING   AND    VENTILATING   BUILDINGS. 


it  can  be  located  at  a  distance  from  the  vanes.  For  measur- 
ing the  velocity  of  the  wind  an  anemometer,  which  consists 
of  hemispherical  cups  mounted  on  a  vertical  axis,  is  much 
used.  The  anemometers  are  all  calibrated  by  moving  them 
in  still  air  at  a  constant  velocity  and  noting  the  readings 
of  the  dials.  This  is  usually  done  by  mounting  the  anemom- 
eter rigidly  on  a  long  horizontal  arm  which  can  be  rotated 
about  a  vertical  axis  at  a  constant  speed. 

When  the  pressure  is  light  it  can  be  measured  by  using  a 
U-tube  partly  filled  with  water.  Such  an  instrument  is  shown 

in  Fig.  12,  attached  to  a  flue.  There 
being  less  than  atmospheric  pressure 
in  the  flue  K,  the  water  rises  in  the 
leg  FE  and  sinks  in  the  leg  DE. 
The  difference  of  level  in  the  two 
legs  is  ab,  which  is  usually  measured 
in  inches.  If  the  flue  is  under  press- 
ure the  water  will  stand  higher  in 
the  leg  DE  than  in  FE,  but  the 
method  of  use  is  essentially  the 
same  in  all  cases. 

In  case  the  pressure  and  velocity 
are  great,  considerable  error  will  be  made  by  using  the  open 
tube  as  above,  and  for  such  a  case  a  Pitot's  tube  arranged  as 
shown  in  Fig.  13  should  be  used. 

This  tube  consists  of  two  parts,  one  of  which  is  straight 
and  enters  at  right  angles  to  the  current  dB\  the  other  is 
curved  so  as  to  face  the  current  at  right  angles,  cA.  These 
are  connected  to  a  U-shaped  manometer  containing  water  or 
some  light  liquid.  The  pressure  in  the  two  tubes  will  be  the 
same  except  for  the  velocity  of  the  current.  This  will  tend 
to  make  the  liquid  stand  higher  in  the  arm  fm  than  in  the 
arm  en.  The  difference  in  elevations  of  these  two  arms  will 
be  the  velocity-head  producing  the  flow.  Call  this  difference 
in  height  h,  and  the  ratio  of  specific  gravity  of  the  liquid 
in  the  tube  and  of  the  gas  in  the  flue  r;  then  will  v  —  V  2ghr. 
That  is,  the  velocity  is  equal  to  8.03  multiplied  by  the  square 
root  of  the  difference  in  height  multiplied  by  ratio  of  weight. 

in  case  water  is  used  in  the  manometer  and  the  gas  is  air 


FIG.  12. — U-SHAPED   WATER 
GAUGE. 


PRINCIPLES   OF    VENTILATION. 


39 


at  a  temperature  of  60  degrees, V  will  equal  813.  Hence  v  will 
equal  228  Vh,  in  which  k  is  in  feet,  and  will  equal  65.7  Vh 
when  //  is  in  inches  of  water.  For  any  other  temperature 
than  60  degrees  this  quantity  must  be  multiplied  by  the 
square  root  of  460  +  the  temperature,  and  then  divided  by 
^5 20.  Practically  for  air  the  velocity  will  equal  228  times 
the  square  root  of  the  difference  in  the  heights  of  the 
columns. 

The  velocity  of  air  may  also  be  computed  by  the  heating 
effects,  provided  the  amount  of  heat  is  accurately  measured 


FIG.  13. — SKETCH  OF  PITOT'S  TUBE  FOR  GREAT  PRESSURES. 

and  the  increase  in  temperature  of  the  air  be  known.  The 
specific  heat  of  air  is  0.238,  hence  the  heat  sufficient  to  warm 
one  pound  of  water  would  heat  (17.238)  =  4.2  pounds  of 
air.  This  at  60  degrees  would  correspond  to  about  231 
cubic  feet.  By  consulting  Table  VIII  the  volume  heated 
I  degree  by  I  heat-unit  at  any  other  temperature  can  be 
found. 

The  total  number  of  cubic  feet  of  air  heated  would  be 
equal  to  the  total  number  of  heat-units  absorbed  divided  by 
the  number  of  degrees  the  air  is  heated,  and  this  result 
multiplied  by  the  volume  of  one  pound  divided  by  the  specific 


40  HEATING   AND    VENTILATING   BUILDINGS. 

heat  (the  latter  number  can  be  taken  directly  from  Table 
VIII).  Having  the  total  amount  of  air  in  a  given  time, 
the  velocity  can  be  obtained  by  dividing  by  the  area  of  the 
passage. 

NOTE. — In  the  shape  of  a  formula  these  results  are  as  follows :  Let 
T equal  temperature  of  discharged  air,  /  that  of  entering  air;  H  equal 
the  total  number  of  heat-units  given  off  per  unit  of  time;  V  equal 
the  number  of  cubic  feet  of  air  heated  I  degree  by  i  heat-unit  (see 
Table  VIII) ;  A  equal  area  of  passage  in  square  feet;  v  equal  velocity 
for  the  same  time  that  the  total  number  of  heat-units  are  taken. 
Then  we  shall  have 


HV 
C  =  Total  amount  of  air  in  cu.  ft.  =  — —  ; 


32.  The  Flow  of  £ir  and  Gases. — The  flow  of  air  obeys 
the  same  general  laws  as  those  which  apply  to  liquids.  The 
gases  are,  however,  compressible,  and  the  volume  is  affected 
very  much  by  'change  of  temperature,  so  that  the  actual  re- 
sults differ  considerably  from  those  obtained  for  liquids. 
These  laws  can  only  be  expressed  in  mathematical  formulae, 
from  which,  however,  practical  tables  are  derived. 

The  flow  of  air  from  an  orifice  takes  place  under  the  same 
general  conditions  as  those  of  liquids,  and  we  have  the  general 
formula  v  =  \/2gh  as  applicable.  In  this  case  h  is  the  head 
which  is  equal  to  the  height  of  a  column  of  air  of  sufficient 
weight  to  produce  the  pressure.  Air  under  a  barometric 
pressure  of  30  inches  and  at  60  degrees  in  temperature  is  813 
times  lighter  than  water.  The  pressure  of  air  is  usually  meas- 
ured by  its  capacity  of  balancing  a  column  of  water  in  a  U- 
shaped  tube  (see  Article  31),  and  this  pressure  is  expressed  in 
inches  of  water.  One  inch  of  water-pressure  is  equivalent  to 
65.7  feet  of  air  at  60°,  and  increases  -g-f^  part  for  each  degree 
of  increase  in  temperature.  The  above  formula  is  only  ap- 
proximate, and  does  not  account  for  the  change  in  temper- 
atures and  of  pressures  due  to  expansion,  although  sufficiently 
accurate  for  the  designing  of  ventilating  apparatus.  Prof. 
Unwin  gives  in  the  article  "  Hydromechanics,"  Encyc.  Brit., 


PRINCIPLES   OF   VENTILATION.  4! 

the    following    formula    for    computing   the   velocity  of   flow 
of  air: 


T  =  absolute  temperature  ; 

Pl  =  absolute  pressure  in  vessel  from  which  flow  takes  place ; 

Pt  =  absolute  pressure  in  surrounding  space. 

To  find  the  volume  discharged  the  velocity  must  be  multi- 
plied by  the  area  and  that  result  by  a  coefficient  which  Prof. 
Unwin  gives  as  follows: 

Conoidal  mouthpieces  of  the  form  of  the  con-  c  = 

tracted  vein,  with  effective  pressures  of  .23  to 

I .  i  atmosphere 097  to  0.99 

Circular  sharp-edged  orifices , 0.563  "  0.788 

Short  cylindrical  mouthpieces 0.81      "  0.84 

The  same,  rounded  at  the  inner  end. .  . . 0.92     "  0.93 

Conical  converging  mouthpieces 0.90     "  0.99 

In  the  flow  of  air  or  gases  through  pipes  the  same  con- 
siderations hold  that  have  been  stated  for  water.  There  is 
the  same  condition  respecting  the  head  which  produces  press- 
ure and  that  which  produces  velocity,  and  in  addition  we  have 
those  changes  due  to  the  compressible  nature  of  the  fluid 
moved. 

Taking  into  account  all  these  conditions,  Prof.  Unwin  gives  as  a 
formula  for  the  flow  of  air  in  a  circular  pipe 


p* 


in  which  u0  =  velocity  in  feet  per  second ; 
c   =  53.15; 

/  =  absolute  temperature; 
g  =32.16; 
d  —  diameter  in  feet ; 


HEATING   AND    VENTILATING   BUILDINGS. 


I  —  length  in  feet ; 

£   =  coefficient  of  friction  =  0.005(1  4- 
p0  =  greatest  absolute  pressure ; 
pi  —  least  absolute  pressure. 

For  a  velocity  of  100  feet  per  second  C  varies  from  0.00484  to 
0.01212  for  a  diameter  varying  from  1.64  ft.  to  0.164  ft- 

For  a  temperature  of  60°  F.  and  for  a  pipe  one  foot  in  diameter  and 
100  feet  long,  C  =  0.006.  For  barometer  reading  of  30  inches,  pressure 
being  expressed  in  inches  of  water,  p6  =  407,  we  have 


from  which  the  third  column  of  the  following  table  is  calculated. 


VOLUME   OF   AIR    DISCHARGED    AT   VARIOUS    PRESSURES. 


Difference  of  Pressure. 

Velocity  in  Feet  pe.'  Second. 

Inches  of  Water. 

Ounces  per  Square 
Inch. 

By  Accurate  Formula 
Pipe  i  Ft.  in  Diam  , 
ioo  Ft.  Long. 

By  Approximate 
Formula. 
(Coefficient  0.7.) 

O.OI 

O.OO6 

4-3 

4-6 

0.05 

0.030 

9.6 

9-5 

O.I 

0.058 

14-5 

14-5 

O.2 

O.  Il6 

19.4 

20.5 

0-3 

0.174 

23.6 

25.1 

0.4 

0.232 

27.4 

29.1 

0.5 

0.289 

30-5 

32.5 

0.6 

0-347 

34-0 

35.2 

0.7 

0.405 

36.0 

38.3 

0.8 

0.463 

39-2 

40.7 

0.9 

o.  512 

41.0 

43-7 

I.O 

0-579 

43-0 

45-7 

2.0 

1.158 

6I..I 

65.2 

3.0 

1-303 

78.0 

78.2 

4.0 

2.316 

85.3 

91.1 

5.0 

2.895 

86.2 

103.3 

6.0 

3.474 

104.0 

II3-3 

7-0 

4.053 

114.0 

122.  1 

8.0 

4.622 

121  .O 

I3O.6 

9.0 

5.221 

128.0 

138.8 

10.  0 

5-790 

136.0 

145.7 

II  .0 

6.369 

I42.O 

153-0 

12.0 

6.948 

148.0 

159.6 

The  preceding   table  gives  the  velocity  of  air  in  feet  per 
second  as  calculated  from  the  accurate  formula  of  Prof.  Unwin, 


PRINCIPLES    OF   VENTILATION. 


43 


and  also  from  the  approximate  formula  v  =  V2gh,  using  a  co- 
efficient of  0.7.  The  table  is  calculated  for  a  barometric  press- 
ure of  30  inches  and  for  a  temperature  of  60°  F.  For  any  other 
temperature  the  results  must  be  multiplied  by  factors  which 
are  calculated  as  explained  below. 

For  the  discharge  at  any  other  temperature  divide  the 
above  results  by  the  square  root  of  520  multiplied  by  460  plus 
the  temperature.  For  temperature  of  32  degrees  multiply  by 
.972,  40  degrees  .981,  50  degrees  .987,  70  degrees  i.oi,  80 
degrees  1.018,  90  degrees  1.03,  IOO  degrees  1.04,  1 10  degrees 
1.05,  1 20  degrees  1.06,  130  degrees  1.07. 

33.  The  Effect  of  Heat  in  producing-  Motion  of  Air.— 
The  effect  of  heat  is  to  expand  air  in  proportion  to  its  abso- 
lute temperature  for  each  degree  of  increase.  If  a  column 
of  air  be  heated  it  will  expand  and  occupy  more  space.  In 
other  words,  a  given  bulk  will  have  less  weight  as  its  tempera- 
ture is  increased  ;  which  has  the  effect  of  producing  lack  of 
equilibrium,  and  the  warmer  air  will  be  replaced  by  colder  air, 
causing  a  velocity  which  is  in  proportion  to  the  change  in  tem- 
perature. The  case  is  analogous  to  the 
action  of  two  fluids  in  the  branches  of 
a  U-tube,  Fig.  14,  DABC, — the  heavier 
fluid  in  DA  and  the  lighter  fluid  in  BC. 
The  action  of  gravity  causes  the  heavier 
fluid  to  flow  downward  and  displace  the 
lighter  fluid,  causing  an  upward  motion 
in  BC.  If  a  volume  of  the  lighter  fluid 
with  height  greater  than  BC  balances 
the  weight  of  the  heavier  fluid  DA,  the  FlG  J4- 

flow  which  is  produced  will  take  place  with  a  head  equal  to  the 
difference  in  height  of  AD,  and  an  equal  weight  of  the  lighter 
fluid.  The  flow  will  take  place  in  the  same  manner  whether 
the  heavier  fluid  be  confined  in  a  tube  arranged  as  in  the  dotted 
lines,  Fig.  14,  or  whether  it  be  drawn  from  a  large  vessel, 
or  from  the  surrounding  air.  Let  the  head  which  produced 
the  draught  be  equal  to  //',  the  height  of  the  flue  BC  as  //  ;  let 
/  be  the  temperature  of  the  outside  air  or  heavier  fluid  and  /' 
that  of  the  lighter  fluid  ;  and  let  a  be  the  coefficient  of  ex- 
pansion, which  for  one  degree  of  temperature  of  air  will  be 


44  HEATING   AND    VENTILATING   BUILDINGS. 


.     Since  the  expansion  is  directly  proportional  to  the  in- 
crease  in  temperature,  we  shall  have  in  general  : 

h  h  +  K   .  ,,       ha(t'  -f) 

-  =  —      —  ,  from  which      ft  =  -  •  —  —  . 
i  +  at       i  +  at'  i  +  at 


By  substituting  for  a  its  value  ^fo,  we  shall  have  the  following  for 
the  head  producing  the  flow  in  case  air  is  the  moving  fluid : 

V  -      k(t>  ~  *>       =  h(?  ~  t} 

-460(1  +4-ioO         460 +  /' 

460  + 1  is  the  absolute  temperature  of  the  air. 

The  velocity  is  equal  to  the  square  root  of  twice  the  force  of  gravity, 
32.16,  into  the  head  which  produces  the  flow,  as  follows: 


The  velocities  given  above,  multiplied  by  60  and  by  the  area  of  cross- 
section,  will  give  the  discharge  in  cubic  feet  per  minute.  Mr.  Alfred  R. 
Wolff  takes  the  actual  discharge  as  0.5  of  that  given  by  the  formula,  so 
that  the  actual  discharge  in  cubic  feet  per  minute  would  be,  with  50 
per  cent  allowance  for  friction, 


460  +  / 

in  which  F  equals  the  area  of  cross-section  of  the  flue  in  square  feet. 
The  table  on  next  page  gives  the  discharge  per  square  foot  of  area  of 
flue  for  various  temperatures  and  heights  computed  from  the  formula. 

The  above  formulae  are  for  the  discharge  of  air  from  a  flue.  The 
volume,  and  consequently  the  velocity,  for  the  entering  air  will  be  pro- 
portional to  its  absolute  temperature ;  and  hence  to  obtain  the  quantity 
of  air  entering  when  T'  is  the  temperature  at  entering  and  T  that  at  dis- 

460  +  T1 

charging  multiply  the  preceding  formula  by  -- — . 

^.oo  -f~  J. 

34.  The  Inlet  for  Air. — The  air  for  ventilation  is  usually 
warmed  and  a  portion  or  all  of  the  heat  required  for  warming 
is  introduced  at  the  same  time. 


PRINCIPLES   OF   VENTILATION. 


45 


TABLE  SHOWING  THE  QUANTITY  OF  AIR,  IN  CUBIC  FEET, 
DISCHARGED  PER  MINUTE  THROUGH  A  FLUE,  OF  WHICH 
THE  CROSS-SECTIONAL  AREA  IS  ONE  SQUARE  FOOT. 

(EXTERNAL  TEMPERATURE  OF  THE  AIR,  32°  FAHR  ;  ALLOWANCE  FOR  FRIC- 
TION, 50  PER  CENT.) 


Height 
of 
Flue  in 
Feet. 

Excess  of  Temperature  of  Air  in  Flue  above  that  of  External  Air. 

5° 

10° 

15° 

20° 

25° 

30° 

50° 

100° 

150° 

I 

24 

34 

42 

43 

54 

59 

76 

1  08 

133 

5 

55 

76 

94 

109 

121 

134 

167 

242 

298 

10 

77 

1  08 

133 

153 

171 

188 

242 

342 

419 

15 

94 

133 

162 

188 

210 

230 

297 

419 

5U 

20 

108 

153 

188 

217 

242 

265 

342 

484 

593 

25 

121 

171 

210 

242 

271 

297 

383 

541 

663 

30 

133 

1  88 

23O 

265 

297 

325 

419 

593 

726 

35 

143 

203 

248 

286 

32O 

351 

453 

640 

784 

40 

153 

217 

265 

306 

342 

375 

484 

684 

838 

45 

162 

230 

282 

325 

363 

398 

5M 

724 

889 

50 

171 

242 

2Q7 

342 

333 

419 

54i 

765 

937 

60 

188 

264 

325 

373 

42O 

461 

594 

835 

1006 

70 

203 

286 

351 

405 

465 

497 

643 

900 

IH5 

80 

217 

306 

375 

453 

485 

530 

688 

965 

1185 

9° 

220 

324 

393 

460 

516 

564 

727 

1027 

1225 

100 

243 

342 

420 

485 

534 

594 

768 

1080 

1325 

125 

273 

383 

468 

542 

604 

662 

855 

I2IO 

1480 

150 

298 

420 

515 

596 

665 

730 

942 

1330 

1630 

It  is  found  from  experience  that  if  the  velocity  of  the  enter- 
ing air  is  very  great  it  produces  a  disagreeable  current,  which  is 
generally  known  as  a  draught,  and  is  more  or  less  dangerous 
to  health.  The  following  table  from  Loomis'  Meteorology  gives 
the  relation  between  the  velocity  and  force  of  air: 

RELATION    BETWEEN   VELOCITY   AND    FORCE   OF   AIR. 


Sensation. 

Velocity. 

Pressure, 
Lbs.  per  Sq. 
Foot. 

Miles  per 
Hour. 

Feet  per 
Second. 

2 

4 
12.5 

25 
35 
45 
60 
70 
So 

IOO 

2.92 
5.85 
IS.  3 
36.6 

5L5 
66 
-88 
-105 

H7 
1146 

O.O2 
0.08 
0.750 

3-0 
6 

IO 

18 
24 
3i 
49 

Gently  pleasant      .  .  . 

Pleasant  brisk  

Very  brisk    

High  wind                     . 

Verv  high  wind  *  

Violent  gale     .            . 

Hurricane  ...        

Most  violent  hurricane.. 

46  HEATING   AND    VENTILATING   BUILDINGS. 

It  is  quite  generally  agreed  that  the  velocity  of  the  entering 
air  should  not  exceed  four  to  six  feet  per  second  unless  it  can 
be  introduced  in  such  a  position  as  to  make  an  insensible  cur- 
rent. The  table  which  has  just  been  given,  while  only  approxi- 
mately correct,  gives  a  very  fair  idea  of  the  sensations  produced 
by  air-currents  of  different  velocities  and  pressures,  and  is  use- 
ful in  fixing  limiting  values. 

The  most  effective  location  for  the  air-inlet  is  probably  in 
or  near  the  ceiling  of  a  room,  although  authorities  differ  much 
in  this  respect.  The  advantages  of  introducing  warm  air  at  or 
near  the  top  of  the  room  are  :  first,  the  warmer  air  tends  to  rise 
and  hence  spreads  uniformly  under  the  ceiling;  second,  it 
gradually  displaces  other  air,  and  the  room  becomes  filled  with 
pure  air  without  sensible  currents  or  draughts  ;  third,  the  cooler 
air  sinks  to  the  bottom  and  can  be  taken  off  by  a  ventilating, 
shaft.  So  far  as  the  system  introduces  air  at  the  top  of  a  room 
it  is  a  forced  distribution,  and  produces  better  results  than 
other  methods.  When  the  inlet  is  placed  in  the  floor  or  near 
the  bottom  part  of  the  walls  it  is  a  receptacle  for  dust  from  the 
room,  and  a  lodging-  and  breeding-place  for  microbe  organisms. 
In  the  ventilation  of  large  buildings  the  inlets  can  usually  be 
located  in  the  ceiling,  especially  if  the  lighting  be  done  by 
electricity  or  in  some  manner  not  affected  by  air-currents. 

Some  experiments  were  made  by  Mr.  Warren  R.  Briggs,  of 
Bridgeport,  Conn.,  on  the  subject  of  the  proper  method  of 
introducing  pure  air  into  rooms  and  the  best  location  for  the 
inlet  and  outlet.  The  experiments  were  conducted  with  a 
model  having  about  one  sixth  of  the  capacity  of  a  schoolroom 
to  which  the  perfected  system  was  to  be  applied.  The  move- 
ments of  the  air  in  the  model  of  the  building  were  made  visi- 
ble by  mingling  the  inflowing  air  stream  with  smoke,  which 
rendered  all  the  changes  undergone  by  it  in  its  passage  appar- 
ent to  the  eye. 

The  results  of  the  experiments  are  shown  graphically  in  the 
six  sketches.  Figs.  15  to  20.  In  each  case  the  distribution  of 
the  fresh  air  is  indicated  by  the  curved  lines  of  shading.  A 
study  of  these  sketches  is  very  suggestive,  as  it  indicates  the 
best  results  when  the  inlet  is  on  the  side  near  the  top,  and  the 
outlet  is  in  the  bottom  and  near  the  centre  of  the  room.  The 


PRINCIPLES   OF   VENTILATION. 


47 


tendency  of  the  entering  air  to  form  air-currents  or  draughts, 
which  in  some  instances  tend  to  pass  out  without  perfect  dif- 
fusion, is  well  shown.  This  tendency  is  less  as  the  velocity  of 
the  entering  air  is  reduced,  and  we  probably  get  nearly  per- 
fect diffusion  in  every  case  where  the  outlet  is  well  below  that 
of  the  inlet,  provided  the  velocity  of  the  entering  air  is  small 
— less  than  4  feet  per  second. 


FIG.  15.— AIR  INTRODUCED  AT  BOTTOM,  DISCHARGED  AT  TOP. 


FIG.  16.— AIR  INTRODUCED  ON  SIDE,  DISCHARGED  AT  TOP. 


FIG.  17.— AIR  INTRODUCED  ON  SIDE,  DISCHARGED  ON  OPPOSITE  SIDE. 


48  HEATING  AND    VENTILATING  BUILDINGS. 


FIG.  18.— AIR  ADMITTED  ON  SIDE,  DISCHARGED  NEAR  BOTTOM. 


FIG.  19. — AIR  ADMITTED  AT  BOTTOM,  DISCHARGED  NEAR  BOTTOM. 


FIG.  20.— INLET  NEAR  TOP,  DISCHARGE  NEAR  BOTTOM. 

35.  The  Outlet  for  Air.— The  outlet  for  air  should  be  as 
near  the  bottom  of  a  room  as  possible,  and  it  should  be  con- 
nected with  a  flue  of  ample  size  maintained  at  a  temperature 
higher  than  that  of  the  surrounding  air,  unless  forced  circula- 


PRINCIPLES   OF    VENTILATION. 


49 


tion  is  in  use,  in  which  case  the  excess  of  pressure  in  a  room 
will  produce  the  required  circulation.  If  the  temperature 
in  a  room  is  higher  than  that  of  the  surrounding  air,  and  if  the 
flue  leading  to  the  outside  air  can  be  kept  from  cooling  and  is 
of  ample  size  and  well  proportioned,  the  amount  of  air  which 
will  be  discharged  will  be  given  quite  accurately  by  the  tables 
referred  to.  These  conditions  should  lead  us  to  locate  vent- 
flues  on  the  inside  walls  of  a  house  or  building,  and  where  they 
will  be  kept  as  warm  as  possible  by  the  surrounding  bodies. 
If  for  any  reason  the  temperature  in  the  flue  becomes  lower 
than  that  of  the  surrounding  air  the  current  will  move  in  a  re- 
verse direction,  and  the  ventilation  system  will  be  obstructed. 

The  conditions  as  to  size  of  the  outlet  register  are  the  same 
as  those  for  the  inlet ;  the  register  should  be  of  ample  size,  the 
opening  should  be  gradually  contracted  into  the  flue,  and  every 
precaution  should  be  taken  to  prevent  friction  losses. 

36.  Ventilation-flues. — The  size  of  ventilation-flue  will 
depend  to  a  great  extent  upon 
the  character  of  system  adopted, 
but  will  in  all  cases  be  computed 
as  previously  explained.  A  prac- 
tical system  of  ventilation  gener- 
ally is  intimately  connected  with 
a  system  of  heating,  and  the  vari- 
ous problems  relating  to  the  size 
and  construction  of  ventilating 
ducts  will  be  considered  later.  In 
general  the  ducts  should  be  of 
such  an  area  as  not  to  require  a 
high  velocity,  since  friction  and 
eddies  are  to  a  great  extent  due 
to  this  cause. 

The  size    of    the    ventilating 
duct  can  be  computed,  knowing 
its   rise,   length,   and   the    differ- 
ence of  temperature  by  dividing 
the  total  amount  to  be  discharged       FIG.  21.— VENTILATION-FLUE. 
by  the  amount  flowing  through  one  square  foot  of  area  of  the 
flue  under  the  same  conditions. 


5O  HEATING   AND    VENTILATING   BUILDINGS. 

In  introducing  heated  air  into  a  room,  it  is  very  much  bet- 
ter to  bring  in  a  large  volume  heated  but  slightly  above  the 
required  temperature  of  the  room  rather  than  a  small  volume 
at  an  excessively  high  temperature.  If  the  temperature  of  the 
air  be  brought  in  25  degrees  above  that  of  the  air  in  the  room, 
the  discharge  in  a  flue  one  square  foot  in  area  would  be  in 
cubic  feet  per  minute,  171  for  a  height  of  10  feet,  271  for  a 
height  of  25  feet,  342  for  a  height  of  40  feet.  By  referring  to 
the  table,  Article  33,  the  discharge  for  any  condition  can  be 
readily  determined. 

As  the  difference  of  temperature  of  the  air  in  the  room 
and  outside  may  usually  be  taken  as  20°,  the  velocity  in  feet 
per  minute  for  heights  corresponding  to  the  distance  of  floor 
to  roof  in  a  building  of  3  stories  would  be  about  as  follows  : 
ist  floor,  306  ;  2d  floor,  242  ;  attic  or  top  floor,  188, — or  about 
5,  4,  and  3  feet  per  second.  For  air  discharged,  the  order  of 
the  velocities  would  be  reversed  on  the  particular  floors.  The 
area  of  the  flue  would  be  found  by  dividing  the  total  air  re- 
quired per  second  by  these  numbers. 

The  general  arrangement  for  heating  the  air  and  introduc- 
ing it  into  a  room  is  shown  in  Fig.  21.  In  this  case  the  cold 
air  is  drawn  in  at  D  and  delivered  into  the  chamber  C,  whence 
it  passes  through  the  heater,  thence  into  the  flue,  entering  the 
room  at  the  register  B.  The  vitiated  air  enters  the  ventilating 
flue  at  E. 

37.  Summary  of  Problems  of  Ventilation. — From  the 
foregoing  considerations  it  is  to  be  noted  that  the  practical  prob- 
lems of  ventilation  require  the  introduction,  first,  of  thirty  or 
more  cubic  feet  of  air  per  minute  for  each  occupant  of  the 
room,  and  in  addition  sufficient  air  to  provide  perfect  combus- 
tion for  gas-jets,  candles,  etc.,  which  are  discharging  the  prod- 
ucts of  combustion  directly  into  the  room.  Second,  the  prob- 
lem requires  the  fresh  air  to  be  introduced  in  such  a  manner 
as  to  make  no  sensible  air-currents,  and  to  be  in  such  quanti- 
ties as  to  keep  the  standard  of  contamination  below  a  certain 
amount.  This  problem  can  be  solved  by  either,  first,  moving 
the  air  by  heat,  in  which  case  the  motive  force  is  very  feeble 
and  likely  to  be  counteracted  by  winds  and  adverse  conditions  ; 
second,  by  moving  the  air  by  fans  or  blowers,  in  which  case 


PRINCIPLES   OF    VENTILATION.  51 

the  circulation  is  more  positive,  and  less  influenced  by  other 
conditions. 

The  methods  for  meeting  these  conditions  will  be  given 
under  appropriate  heads  in  later  articles. 

It  will  generally  be  found  much  more  convenient  to  esti- 
mate the  air  required,  not  in  cubic  feet  per  minute  for  each 
person,  but  by  the  number  of  times  the  air  in  the  room  will 
need  to  be  changed  per  hour.  If  the  number  of  people  who 
occupy  a  room  be  known,  and  each  one  requires  30  cubic 
feet  of  air  per  minute  or  1800  cubic  feet  per  hour,  one  can 
easily  compute  the  number  of  times  the  air  in  a  room  must  be 
changed  to  meet  this  requirement.  Thus  a  room  containing 
1800  cubic  feet,  in  which  five  people  might  be  expected  to  stay, 
would  need  to  have  the  air  changed  five  times  per  hour  in 
order  to  supply  the  required  amount  for  ventilation  purposes. 

By  consulting  the  table  Properties  of  Air,  No.  VIII,  it  will 
be  seen  that  one  heat-unit  contains  sufficient  heat  to  warm  55 
cubic  feet  of  air,  at  average  pressures  and  temperatures,  one 
degree ;  so  that  practically  to  find  the  number  of  heat-units  re- 
quired for  warming  the  air  one  degree  we  must  simply  divide 
by  55  the  number  of  cubic  feet  to  be  supplied,.  If  the  cubic 
contents  of  the  room  is  to  be  changed  from  five  to  ten  times 
per  hour,  we  can  very  readily  make  the  necessary  computations 
by  knowing  the  volume  of  the  room. 

Even  in  the  case  of  direct  heating,  where  no  air  is  purposely 
supplied  for  ventilation,  there  will  be  a  change  by  diffusion  of 
the  air  in  a  room  which  the  writer  has  found-practically  met 
by  an  allowance  equal  to  one  to  three  changes  in  the  cubic 
contents  per  hour,  which  serves  to  supply  heat  for  ventilation 
purposes  in  addition  to  that  transmitted  by  the  walls. 

The  number  of  times  that  air  will  need  to  be  changed 
per  minute  in  a  given  room  will  depend  upon  its  size  as  com- 
pared with  the  number  of  occupants.  If  we  take  the  smallest 
size  of  rooms,  in  which  we  allow  only  400  cubic  feet  of  space 
per  occupant,  a  supply  of  30  cubic  feet  per  minute  would 
change  the  air  in  this  space  in  13^  minutes,  or  at  the  rate  of  4^ 
times  per  hour.  If  600  cubic  feet  are  supplied  per  occupant, 
the  air  of  the  room  would  be  changed  once  in  20  minutes,  or 
at  the  rate  of  3  times  per  hour.  The  following  table  may  be 


HEATING   AND    VENTILATING   BUILDINGS. 


of  practical  value,  as  it  shows  the  number  of  changes  per  hour 
required  to  supply  each  person  with  30  cubic  feet  per  minute 
when  the  space  supplied  is  as  given  in  the  table : 


Space  to  each  Person. 
Cubic  Feet. 


IOO. 
200, 
300. 
400. 
500, 
6OO. 
700. 
800 
90O 


Number  of  Times  Air  to  be 
Changed  per  Hour. 

18 


9 
6 

4-5 
3-6 

3 

2.6 

2.25 

2 


38.  Dimensions  of  Registers  and  Flues. — The  approxi- 
mate dimensions  of  registers  and  flues  can  be  computed  from 
considerations  of  the  limiting  velocity  of  entering  air. 

For  residence  heating  the  velocity  in  flues  is  likely  to  be  as 
follows,  in  feet  per  second  :  . 


Warm-air 
Duct. 

Ventilating 
Duct. 

Entering  Air 
at  Register. 

Discharge  Air 
at  Register. 

First  story 

2    C  to  4. 

6 

a 

4 

Second  story     •          •  •  • 

e 

c 

3 

4 

Third  story    

6 

4 

3 

3 

Attic  floor 

7 

•3 

a 

2i 

The  velocity  per  hour  is  3600  times  that  per  second.  The 
area  of  the  duct  can  be  found  by  dividing  the  cubic  feet  of  air 
needed  per  hour  by  3600  times  that  in  the  above  columns.  If 
the  air  required  is  taken  as  a  certain  number  of  times  the 
cubic  contents  of  the  room  the  following  method  is  applicable: 

If  we  denote  the  cubic  contents  of  a  room  by  C,  the  num- 
ber of  times  the  air  is  to  be  changed  per  hour  by  «,  the 
velocity  in  feet  per  second  by  V,  then  will  the  area  in  square 

c        A          HC         T  •     r.  nC 

feet  A  =    — — ±- .     In  square  inches  a  =  — -  . 

3600  V  2$V 

The  following  table  gives  the  net  area  in  square  inches  for 


PRINCIPLES   OF    VENTILATION. 


53 


each  1000  cubic  feet  of  space,  of  either  the  hot  air  or  ventilat- 
ing register,  for  any  required  velocity  of  the  air.  The  net 
area  is  about  0.7  the  nominal  area.  (See  Table  of  Registers, 
Article  144.) 

AREA    IN   SQUARE   INCHES   FOR    EACH    1UOO   CUBIC   FEET 
OF   SPACE. 


Velocity,  Feet 
per  Second. 

Number  of  Times  Air  changed  per  Hour. 

• 

2 

i 

4 

5 

6 

8 

10 

I 

40 
2O 

13-3 
1O 
8 
6.7 
5 
4 
2.7 

2 

1.6 
1-3 

80 

40 
26 
20 
16 
13 
4 
8 

5-3 
4 

3-4 
2-7 

120 
60 
40 
30 
24 
2O 

15 
12 

8 
6 
4-8 

4 

1  60 
80 

53 
40 

34 
27 

20 
I? 

"•  3 
8-5 
6.8 

5-7 

200 
100 

67 
50 
40 

33 
25 

20 

13-3 
TO 

8 
6-7 

.240 
120 
80 
60 
48 
40 
30 
24 
16 

12 
9.6 

8 

320 
1  60 
107 
80 
64 

53 

20 
32 
21 

16 

12.8 

10.5 

400 

2OO 

133 

100 

80 
67 
50 
40 
26.6 

20 
16 

13.3 

2      

a 

5. 

6  

8 

10  

je.  . 

2O 

2e 

OQ.  . 

CHAPTER    III. 
AMOUNT   OF   HEAT   REQUIRED    FOR   WARMING. 

39.  Loss  of  Heat  from  Buildings. — Heat  is  required  to 
warm  the  air  of  a  room   to  a  given  temperature,  to  supply 
the  loss  due  to  the  radiation  and  conduction  of  heat  from 
windows   and  walls,   and  to   supply  the  heat   for   the  air  re- 
quired for  ventilation.     The  amount  of  heat  required  for  these 
various  purposes  will  depend  largely  upon  the  construction  of 
the  building  and  the  supply  needed  for  ventilation  purposes. 

This  question  was  investigated  experimentally  by  Peclet^ 
and  it  also  received  attention  by  Tredgold  at  about  the  same 
time,  and  has  been  more  recently  investigated  by  the  German 
Government.  Peclet's  investigations  were  carried  out  with 
extreme  care,  and  reduced  to  general  laws.  He  divides  the 
loss  into  two  parts  :  first,  that  from  the  windows  ;  second,  that 
lost  by  conduction  through  the  walls.  He  considers  the  loss 
in  each  case  from  the  exterior  of  the  wall  as  due  in  part  to 
radiation  and  in  part  to  convection. 

40.  Loss  of  Heat  from   Windows. — The  values  which 
Peclet  found  for  glass,  reduced  to  English  measures,  were  as 
follows  :* 

LOSS  PER  SQUARE  FOOT  PER  DEGREE  DIFFERENCE  OF  TEM- 
PERATURE FAHR.  PER  HOUR  FOR  WINDOWS. 


Height  of  Window. 

3  ft.  3  in.    !    6  ft.  7  in. 

10  ft. 

13  ft.  3  in. 

16  ft.  3  in. 

Loss  in  B.  T.  U.  per) 
square  foot  per  degree  ! 
difference  of  tempera-  j 
ture,  j 

0.98            O.Q45 

i 

o-93 

0.92 

0.91 

*  The  general  formula  which  Peclet  gives  as  expressing  this  loss  is  as  fol- 
lows :  M—\(T—  §)(K-\-K'),  in  which  T  equals  temperature  of  the  room,  6  = 
temperature  of  the  air,  K  =  coefficient  loss  for  radiation,  JC'=  coefficient  loss 
for  convection.  A"  varies  with;  the  height.  A' is  constant,  and  in  all  cases 
equal  to  291  when  the  temperature  is  measured  by  a  centigrade  thermometer. 
The  values  of  the  coefficients  A' and  K1  were  determined  by  experiment. 

54 


AMOUNT  OF  HEAT  REQUIRED   FOR    WARMING.          $5 

For  multiple  glass  the  above  numbers  are  to  be  multiplied 
by  the  following  coefficients  : 

21  2 

Double  — ,     Triple  -,     Quadruple  -,     n  layers 


3  2-  5'  ,+« 

The  coefficients  given  above  do  not  differ  greatly  from 
unity  for  each  square  foot  of  single  glass  and  two  thirds  as- 
much  for  each  square  foot  of  double  glass  per  degree  differ- 
ence of  temperature. 

Tredgold,  in  his  work  on  "  Warming  and  Ventilation," 
states  that  one  square  foot  of  glass  will  cool  90  cubic  feet  of 
air  one  degree  per  hour.  This  is  about  equivalent  to  1.7  B.  T. 
U.  per  degree  difference  of  temperature  per  hour.  This 
number  was  used  in  computation  by  both  Tredgold  and  Hood, 
neglecting  the  cooling  effect  of  the  walls.  Hood,  in  his  work 
"Warming  of  Buildings,"  third  edition,  page  213,  gives  various 
other  experiments  of  the  same  nature. 

Mr.  Alfred  R.  Wolff,  M.E.,  in  a  recent  pamphlet  gives  co- 
efficients adopted  by  the  German  Government,  as  follows  : 

Heat  transmission  in  B.  T.  U.  per  square  foot  per  hour,  per 
degree  difference  of  temperature  :  Single  window,  1.09;  single 
skylight,  1.118:  double  window,  0.518;  double  skylight,  0.621. 
These  coefficients  are  to  be  increased,  as  explained  in  the  next 
article,  for  exposed  buildings. 

41.  Loss  of  Heat  from  Walls  of  Buildings. — The  loss  of 
heat  depends  upon  the  material  used,  its  thickness,  the  num- 
ber of  layers,  the  difference  of  temperature  between  outside 
and  inside  surfaces,  and  air  exposure. 

The  problem  is  one  very  difficult  of  theoretical  solution, 
and  we  depend  principally  for  our  knowledge  on  the  results  of 
experiments. 

The  following  tables  were  computed  from  formulae  given  by 
Peclet  and  reduced  to  English  measures  by  the  writer:* 


*  M  =  CQ(  T  -  9)  -r-  (2(7+  Q_e\  in  which  Q  -  K  +  K' ,  e  =  thickness, 
and  C  —  coefficient  of  conduction.  See  Table  XlV.  Other  values  as  on  page 
54- 


HEATING   AND    VENTILATING   BUILDINGS. 


AMOUNT  OF  HEAT  IN  BRITISH  THERMAL  UNITS  PASSING 
THROUGH  WALLS  PER  SQUARE  FOOT  OF  AREA  PER  DEGREE 
DIFFERENCE  OF  TEMPERATURE  PER  HOUR. 


Single  Wall. 

Wall  with  Air-space. 

Thickness, 

inches. 

Brick  or  Stone. 

Wood.* 

Brick  or  Stone. 

4 

0-43 

O.  12 

0.36 

8 

0-37 

0.065 

0.30 

12 

0.32 

0.045 

0.25 

16 

0.28 

0.033 

0.21 

18 

0.26 

0.031 

O.IQ 

20 

0.25 

0.03 

0.18 

24 

0.24 

O.O2Q 

0.17 

28 

0.22 

O.O27 

0.15 

32 

O.2I 

0.025 

0.13 

36 

0.20 

O.O2O 

0.12 

40 

0.18 

O.OlS 

O.  IO 

Mr.  Alfred  R.  Wolff,  in  a  lecture  before  the  Franklin  In- 
stitute,! gives  coefficients  for  loss  of  heat  from  walls  of  various 
thicknesses,  which  he  translated  from  and  transformed  into 
American  units  from  tables  prescribed  by  the  German  Govern- 
ment as  follows : 

FOR  EACH  SQUARE  FOOT  OF  BRICK  WALL. 


Thickness  of  wall  = 

4" 

8" 

12" 

16" 

20" 

24" 

28" 

32" 

36" 

40" 

Loss  of  heat  per  square 
foot  per  hour  per 
degree  difference  of 
temperature  .... 

o  68 

o  46 

O    ^2 

o  26 

O    21 

O    2O 

O    I  Id. 

O    I  ^ 

o  1  29 

o  115 

I  square  foot,  wooden  beam,  planked  j  as  flooring. . .  .  K  =  0.083 

over  or  ceiled,  {  as  ceiling K  =  o.  104 

i  square  foot,  fireproof  construction,  j  as  flooring.  ...   K  =  o.  124 

floored  over,  \  as  ceiling K  =0.145 

i  square  foot,  single  window K  —    1 .09 

i  square  foot,  single  skylight K  —  i .  1 1 5 

i  square  foot,  double  window  ...    K  =  0.518 

i  square  foot,  double  skylight K =  0.621 

I  square  foot,  door K  =0.414 


*  This  experiment  applies  to  solid  wood  ;  it  is  evidently  of  little  use  when 
applied  to  wooden  buildings,  since  these  buildings  generally  present  so  many 
opportunities  for  loss  of  heat  through  crevices. 

f  Lecture  on  Heating  of  Large  Buildings,  published  in  pamphlet  form. 


AMOUNT   OF  HEAT  REQUIRED    FOR    WARMING. 


57 


These  coefficients  are  to  be  increased  respectively  as  fol- 
lows : 

Ten  per  cent  where  the  exposure  is  a  northerly  one  and  the  winds 
are  to  be  counted  on  as  important  factors. 

Ten  per  cent  when  the  building  is  heated  during  the  daytime  only, 
and  the  location  of  the  building  is  not  an  exposed  one. 

Thirty  per  cent  when  the  building  is  heated  during  the  daytime  only, 
and  the  location  of  the  building  is  exposed. 

Fifty  per  cent  when  the  building  is  heated  during  the  winter  months 
intermittently,  with  long  intervals  (say  days  or  weeks)  of  non-heating. 

Mr.  Wolff  has  arranged  the  results  in  a  graphical  form  (Fig. 
22),  so  that  the  values  for  heat  losses  can  be  obtained  by  in- 
spection. 


.10  20  &>  40  60  CO  70  _  __         

FIG.  22. — WOLFF'S  DIAGRAM  OF  Loss  OF  HEAT  FROM  WALLS 

In  this  diagram  distance  in  horizontal  direction  is  the  re- 
quired difference  in  temperature  between  that  of  the  room  and 
the  outside  air  ;  the  various  diagonal  lines  correspond  to  the 
different  radiating  surfaces  of  the  building,  floors,  ceiling,  doors, 
windows,  etc.  The  heat  transmitted  per  square  foot  of  sur 
face  per  hour  is  given  by  the  numbers  in  the  vertical  column. 


58  HEATING   AND    VENTILATING   BUILDINGS, 

The  German  Government  require  computations  to  be  made  on  the 
following  assumed  lowest  temperatures  :* 

External  temperature 4°  Fahr. 

Assumed  lowest  temperature  of  non-heated  cellar 
and  other  portions  of  building  permanently  non- 
heated  32 

Vestibules,  corridors,  etc.,  non-heated,  and  at  fre- 
quent intervals  in  direct  contact  with  external 

air 23 

(  Metal  and  slate  roofs. . .    14' 

Air-spaces  between  roof  j  Denser  methods  of  roof- 
and  ceiling  of  rooms,  j  ing,  such  as  brick,  con- 

[     crete,  etc 23° 

As  the  temperature  to  be  attained  in  rooms  of  various  kinds,  the 
German  Government  prescribes  for — 

Stores  and  dwellings 68°  Fahr. 

Halls,  auditoriums,  etc 64° 

Corridors,  staircase-halls,  etc 54° 

Prisons,  occupied  by  day  and  night 64° 

In  making  calculations  for  heat  losses  for  buildings  in 
America  the  minimum  external  temperature  is  usually  assumed 
as  zero  Fahr.,  and  the  required  temperature  in  stores  and  dwell- 
ings as  70  degrees.  In  many  portions  of  the  country  the  cor- 
ridors, staircase,  halls,  etc.,  are  required  to  be  from  65°  to  68°; 
while  in  other  portions  of  the  country  the  halls  are  required  to 
be  as  warm  as  the  living-rooms.  In  the  preceding  computa- 
tions no  allowance  has  been  made  for  the  heat  carried  off  in 
the  process  of  ventilation,  nor  for  that  supplied  from  the  bodies 
of  people  in  the  room,  gas,  electric  lights,  etc. 

The  loss  of  heat  from  walls  and  glass  surfaces  has  also  been 
considered  by  Leicester  Allen,  Metal  Worker,  October,  1892  ; 
and  by  John  J.  Hogan.  Mr.  Hogan  gives  the  cooling  power 
of  one  square  foot  of  glass  as  1.57  heat-units,  and  that  of  a 
brick  wall  4  inches  thick  as  .231 — results  which  are  somewhat 
different  from  those  given  by  Mr.  Wolff. 

42.  Heat  required  for  Purposes  of  Ventilation. — In  ad- 
dition to  the  loss  of  heat  through  walls  of  buildings,  more  or 
less  heat  will  be  carried  off  by  the  air  which  escapes  from 
various  cracks  and  crevices. 

By  consulting  Table  VIII  it  will  be  seen  that,  for  ordinary 

*  Lecture  by  Alfred  Wolff  before  Franklin  Institute. 


AMOUNT  OF  HEAT  REQUIRED   FOR    WARMING.          59 

temperatures  and  pressures,  55  cubic  *  feet  of  air  will  absorb  one 
heat-unit  in  being  warmed  one  degree  F.,  and  hence  can  be 
considered  the  equivalent  of  one  pound  of  water. 

The  heat-units  required  for  ventilation  can  then  be  found 
by  multiplying  the  number  of  cubic  feet  of  air  by  the  differ- 
ence of  temperature  between  warm  and  outside  air,  and  divid- 

ing by  55-t 

Total  Heat  Required.  —  By  referring  to  the  values  for 
heat  losses  given  by  Wolff  and  Peclet,  it  will  be  noted  that  a 
fair  average  value  would  be  I  heat-unit  for  glass  and  0.25  heat- 
unit  for  walls  per  degree  difference  of  temperature  per  square 
foot  per  hour.  Usually  we  can  neglect  all  inside  walls,  floors, 
and  ceilings,  and  consider  only  the  exposed  or  outside  walls 
with  sufficient  accuracy. 

For  direct  heating  of  residences  it  seems  necessary  to  con- 
sider the  air  of  halls  changed  3  times  per  hour,  that  of  rooms 
on  first  floor  2  times  per  hour,  and  that  of  rooms  on  the  upper 
floors  once  per  hour,  to  account  for  changes  taking  place  by 
diffusion. 

If  C  represent  cubic  contents  of  room,  W  the  area  of  ex- 
posed wall  surface,  G  the  area  of  glass,  n  the  number  of  times 
air  is  changed  per  hour,  /  the  difference  of  temperature  be- 
tween air  in  room  and  outside,  we  have,  as  a  general  formula 
for  heat  required,  in  heat-units  per  hour, 


Very  elaborate  methods  of  computing  the  loss  of  heat 
through  the  walls  of  a  building  are  given  by  Box  in  his  Treatise 
on  Heat  as  a  translation  from  the  experiments  by  P^clet.J 
These  methods  have  in  some  instances  been  employed  by 
amateurs  in  this  art  in  computing  the  loss  of  heat  through  the 
walls.  It  seems  necessary  to  remark  here  that  the  coefficients 
obtained  by  Peclet  are  accurate  only  under  the  conditions  gov- 

*  This  quantity  varies  somewhat  with  barometric  pressure  and  temperature. 
f  If  C  —  cubic  contents  of  room,  n  the  number  of  times  air  is  changed,  /the 

difference  of  temperature,  //  the  heat-units  for  ventilation,  h  =  —  /. 
J  Traite  de  la  Chaleur,  Paris. 


HEATING   AND    VENTILATING   BUILDINGS. 

erning  his  experiments,  and  there  is  little  or  no  proof  that  the 
loss  of  heat  from  the  walls  of  a  building  was  ever  actually 
measured  by  him.  Recent  writers*  on  heat  have  found  that 
Peclet  made  an  error  in  the  position  of  the  decimal  point  in 
reporting  the  coefficient  of  conductivity,  and  that  his  values  in 
consequence  were  ten  times  too  small  at  least  for  metals  of 
high  conductibility  and  were  probably  in  error  for  all  cases. 
Not  only  are  the  coefficients  given  by  Peclet  doubtful,  but  his 
method  or  rule  for  computing  the  heat  lost  through  the  walls 
is  erroneous.  For  computing  the  loss  of  heat  he  employs 
formulae  of  the  same  general  nature  as  those  given  on  page  63 
for  loss  of  heat  from  a  heated  body  in  still  air.  For  such  cases 
there  is  a  decrease  in  the  loss  of  heat  per  unit  of  area  with  in- 
crease in  height,  but  different  conditions  apply  to  the  the  side 
of  a  building  freely  exposed  to  air-currents.  Actually  there 
is  in  many  cases  an. increase  in  heat  transmission,  due  to  stronger 
air-currents  near  the  top  of  a  building.  The  application  of  the 
formulae  quoted  by  Box  f  shows  that  the  loss  of  heat  from  a 
building  with  one  side  exposed  is  greater  per  unit  of  area  than 
from  a  building  with  all  sides  exposed,  which  is  rarely  ever  true. 
The  principal  objection  to  the  methods  referred  to  lies  in  the 
fact  that,  while  the  loss  of  heat  through  the  walls  is  computed 
with  great  elaborateness  of  detail,  no  consideration  is  given  to 
the  heat  required  to  warm  the  air,  which  in  spite  of  all  precau- 
tions will  constantly  enter  and  leave  an  apartment  and  for 
which  considerable  heat  is  in  all  cases  required. 

Practically  there  is  little  or  no  difference  in  the  amount  of 
heat  required  to  warm  a  wooden  or  a  brick  building,  which  is 
due  to  the  fact  that  air-spaces  lined  with  heavy  building-paper 
make  the  heat  losses  in  the  one  practically  as  small  as  in  the 
other.  There  is,  however,  a  great  difference  in  the  amount  of 
heat  transmitted  through  the  walls  of  different  buildings,  due 
to  good  or  bad  construction  or  to  use  of  inferior  or  superior 
materials  ;  this  fact  renders  any  elaborate  formula  for  this  pur- 
pose abortive.  The  best  that  can  be  expected  of  any  rule  is 
agreement  with  the  average  condition. 


*  Theory  of  Heat,  Preston,  London, 
f  A  Practical  Treat/se  on  Heat,  p.  218. 


AMOUNT   OF  HEAT  REQUIRED    FOR    WARMING.        59^ 

The  author  in  two  cases  measured  the  loss  of  heat,  witli 
the  following  results  :*  In  the  first  case  a  room  on  the  second 
floor  with  exposed  side  and  end  had  246  sq.  ft.  of  wall  surface 
and  96  sq.  ft.  of  window  surface.  When  the  air  in  the  room 
was  28  degrees  above  that  outside  the  loss  was  4247  B.  T.  U. 
per  hour,  and  when  27  degrees  above,  was  4240  B.  T.  U.  per 
hour.  To  supply  loss  of  heat  by  the  rule  stated  would  re- 
quire respectively  4410  and  4253  B.  T.  U.  per  hour,  the 
error  varying  from  a  fraction  of  one  per  cent  to  nearly  five 
per  cent.  In  the  second  case  a  test  was  made  in  the  N.  Y. 
State  Veterinary  College ;  this  showed  that  to  maintain  the 
room  31  degrees  warmer  than  the  outside  air  16,000  B.  T.  U. 
were  required  per  minute,  of  which  39  per  cent  escaped  in 
the  ventilation-flues,  and  61  per  cent  passed  by  conduction 
through  the  walls  and  windows.  The  building  was  exposed  on 
all  sides,  was  3  stories  in  height,  had  9281  sq.  ft.  of  glass  and 
31,644  sq.  ft.  of  exposed  wall  surface.  By  the  rule  quoted 
the  building  loss  should  be  532,952  B.  T.  U.  per  hour.  The 
actual  loss  by  experiment  was  9120  B.  T.  U.  per  minute  or 
547,200  B.  T.  U.  per  hour,  which  is  within  two  per  cent  of  that 
called  for  by  the  rule.  In  this  case  the  building  was  of  brick, 
the  thickness  of  walls  varied  from  24  to  16  inches,  the  windows 
had  single  glass. 

The  above  experiments,  which  were  made  on  a  large  scale 
and  en  actual  buildings,  indicate  the  substantial  accuracy  of  the 
rule  quoted. 

Data  regarding  the  number  of  changes  of  air  which  take 
place  per  hour  under  different  conditions  of  direct  heating  in 
buildings  are  still  very  deficient.  The  following  seems  to  be 
reliable : 


Number  of  Changes  of  Air  per  Hour. 

Residence  heating Halls,  3  ;  sitting-room,  etc.,  2  ;  sleeping-rooms,  i. 

Stores First  floor,  2  to  3  ;  second  floor,  \\  to  2. 

Offices 4 .   First  floor,  2  to  2$;  second  floor,  i  \  to  2. 

Churches  and  public  assembly-rooms,     2  to  2\. 

*  Transactions  of  American  Society  of  Heating  and  Veniiiatiog  Enguicexs, 
vols.  in.  and  IV. 


CHAPTER   IV. 
HEAT   GIVEN   OFF   FROM    RADIATING   SURFACES. 

43.  The   Heat  Supplied  by  Radiating  Surfaces. — The 

heat  used  in  warming  is  obtained  either  by  directly  placing  a 
heated  surface  in  the  apartment,  in  which  case  the  heat  is  said 
to  be  obtained  by  direct  radiation,  or  else  by  heating  the  air 
which  is  to  be  used  for  ventilating  purposes  while  on  passage 
to  the  room,  in  which  case  the  heating  is  said  to  be  by  indu 
rect  radiation.  As  air  is  not  heated  appreciably  by  radiant 
heat,  this  latter  term  is  very  clearly  one  which  is  used  in  a 
wrong  sense.  In  this  treatise  we  shall  use  the  terms  direct 
heating  or  radiation  and  indirect  Jicating. 

Direct  heating  is  performed  by  locating  the  heated  surface 
directly  in  the  apartment :  this  surface  may  be  heated  by  fire 
directly,  as  is  the  case  with  stoves  and  fireplaces;  or  it  may 
receive  its  heat  from  steam  or  from  hot  water  warmed  in  some 
other  portion  of  the  premises  and  conveyed  in  pipes.  The 
general  principles  of  warming  are  the  same  in  all  cases,  but  for 
the  case  of  stoves  the  temperature  is  greatly  in  excess  of  that 
for  steam  or  hot-water  heating  surfaces.  The  heat  is  carried 
away  from  the  heated  surface  partly  by  radiation,  in  which  case 
the  heat  passes  directly  in  straight  lines  and  is  absorbed  by 
people,  furniture,  and  objects  in  the  room,  without  warming  up 
the  intervening  air  directly,  and  also  by  particles  of  air  coming 
in  contact  with  the  heated  surface,  which  may  be  the  radiating 
surface,  or  the  people  and  objects  in  the  room  which  have  been 
warmed  by  radiant  heat. 

The  sensation  caused  by  radiant  and  convected  heat  is  quite 
different:  the  radiant  heat  has  the  effect  of  intensely  heating  a 
person  on  the  side  towards  the  source  of  heat,  and  of  producing 
no  warming  effect  whatever  on  the  opposite  side.  The  heat 
which  has  passed  off  by  convection  is  first  utilized  in  warming 
the  air,  and  the  sensation  produced  on  any  person  is  that  of 
loyver  temperature-heat  equably  distributed.  Radiant  and  con- 
Co 


HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES.        6 1 

vected  heat  are  essentially  of  theVsame  nature:  in  the  one  case 
it  is  received  by  the  person  directly  from  the  source  of  heat, 
and  at  a  high  temperature ;  in  the  other  case  it  is  received  from 
the  air,  which  is  at  a  comparatively  low  temperature. 

The  heat  in  passing  through  any  metallic  surface  raises 
its  temperature  an  amount  which  depends  upon  the  facility 
with  which  heat  is  conducted  by  the  body  and  discharged 
from  the  outer  surface.  The  phenomena  of  the  flow  of  heat 
through  any  metallic  substance  can  be  i  E  I  L 

illustrated    by  the   sketch   in    Fig.  23.  A 
If  E  represents  the  source  of  heat,  and 
ABCD  a  section  of  a  metallic  wall  sur- 


rounding,  the  flow  of  heat  takes  place  FIG.  23. 

into  the  metallic  surface,  then  through  the  solid  metal,  and 

finally  through  the  outer  surface. 

It  is  noted  that  the  heat  meets  with  three  distinct  classes  of 
resistances:  first,  that  due  to  the  inner  surface;  second,  that 
due  to  the  thickness  of  the  material;  and  third,  that  due  to  the 
outer  surface.  The  first  and  third  resistances  are  due  to  change 
of  media,  and  when  the  material  under  consideration  is  a  good 
conductor,  constitute  the  principal  portion  of  the  resistance  to 
the  passage  of  heat. 

If  the  resistance  on  the  inner  surface  AB  is  small  and  that 
on  the  outer  surface  CD  is  great,  the  temperature  of  the  metal- 
lic body  will  approach  that  of  the  source  of  heat,  for  the  reason 
that  the  heat  will  be  delivered  to  the  surface  CD  faster  than  it 
is  discharged.  In  this  case  the  thickness  of  the  material  is  of 
little  or  no  importance,  and  the  rate  at  which  heat  will  pass 
will  depend  entirely  upon  the  rapidity  with  which  it  can  be 
discharged  from  the  outer  surface. 

44.  Heat  Emitted  by  Radiation. — Heat  emitted  by  radia- 
tion, per  unit  of  surface  and  per  unit  of  time,  is  independent  of 
the  form  and  extent  of  the  heated  body,  provided  there  are  no 
re-entrant  surfaces  which  intercept  the  rays  of  radiant  heat. 
The  amount  of  heat  projected  from  a  surface  of  such  form  as 
to  radiate  heat  equally  in  all  directions,  depends  only  on  the 
nature  of  its  surface,  the  excess  of  its  temperature  over  that 
of  the  surrounding  air,  and  the  absolute  value  of  its  tem- 
perature. 


^2  HEATING   AND    VENTILATING   BUILDINGS. 

Radiation  of  heat  was  stated  by  Sir  Isaac  Newton  to  be  in 
exact  proportion  to  the  difference  of  temperature  of  the  heated 
surface  and  the  surrounding  media,  but  this  law  was  found  to 
be  inaccurate  by  Dulong  and  Petit.  They  found  that  the 
radiation  increased  at  a  greater  rate  than  the  difference  in  tem- 
perature, and  for  high  temperature,  was  much  in  excess  of  that 
given  by  the  law  of  Newton.  From  a  large  number  of  experi- 
ments on  the  cooling  of  bodies  they  were  able  to  determine  the 
following  law  :  "  The  rate  of  cooling  due  to  radiation  is  the 
same  for  all  bodies,  but  its  absolute  value  varies  with  the 
nature  of  the  surface."  It  is  represented  by  the  formula 


—  I), 


in  which  m  represents  a  number  depending  on  the  nature  of 
the  surface  of  the  body,  a  represents  a  constant  number,  which 
for  the  centigrade  thermometer  is  equal  to  1.0077  and  for  the 
Fahrenheit  above  32°  to  1.00196,  6  the  temperature  of  the  sur- 
rounding air,  and  t  the  excess  of  temperature  of  the  body  over 
that  of  the  surrounding  space. 

P£clet  found  that  if  the  radiant  heat  be  received  by  a  dull 
surface  the  value  of  m  becomes  equal  to  a  constant  124.72  mul- 
tiplied by  K,  a  coefficient  which  depends  on  the  nature  of  the 
surface.  A  table  giving  the  rapidity  of  cooling  for  different 
values  of  difference  of  temperature  in  both  Fahrenheit  and 
metric  units  is  given  on  page  64,  and  the  value  of  the  coeffi- 
cient K  for  different  surfaces,  which  is  to  be  multiplied  by  the 
numbers  which  express  the  relative  rates  of  cooling,  is  given  in 
a  subsequent  table. 

The  results  of  the  experiments  by  Peclet  accord  very  well 
with  recent  experiments  made  in  testing  radiators  for  steam 
and  hot-water  heating.  For  these  cases  either  wrought  or 
cast  iron  is  used,  and  the  difference  in  radiating  power  is  im- 
material. The  construction  of  the  ordinary  form  of  radiator 
is  such  as  to  present  very  little  free  radiating  surface,  as  all  the 
heat  which  impinges  from  one  tube  on  another  is  reradiated 
back,  and  consequently  not  of  use  in  heating  the  apartment. 
The  greater  portion  of  the  heat  removed  is  no  doubt  absorbed 


HEAT  Gll'EN  OFF  FROM  RADIATING   SURFACES.        63 

by  the  air  which  comes  in  contact  with  the  radiator,  or,  in  other 
words,  it  is  removed  by  convection. 

45.  Heat  Removed  by  Convection  (Indirect  Heating). — 
The  heat  removed  by  convection  is  independent  of  the  nature  of 
the  surface  of  the  body  and  of  the  surrounding  absolute  tem- 
perature. It  depends  on  the  velocity  of  the  moving  air,  and  is 
thought  to  vary  with  the  square  root  of  the  velocity.  It  also 
depends  on  the  form  and  dimensions  of  the  body  and  of  the  ex- 
cess of  temperature  over  that  of  the  surrounding  air.  We  are 
indebted  to  Peclet  for  exact  experiments  giving  us  the  value  of 
the  loss  from  this  cause.  Peclet's  experiments  were,  however, 
made  in  ordinary  still  air,  and  if  the  velocity  is  increased  should 
be  multiplied  by  factors  which  will  be  given  later.  The  formulae 
which  Peclet  found  as  applying  to  bodies  of  different  form  were 
as  follows,  the  results  below  being  given  in  heat-units  per  square 
foot  per  hour. 

The  general   formula  for  loss  by  convection   is,  in  metric 
units, 

A  =  o.^2K'tl  233. 

The  values  of  K'  depend  upon  the  form  and  surface  of  the 
body  and  are  as  follows : 

For  a  sphere,  radius  r, 

K'=  1.778  +  0.13/7-. 
For  a  vertical  cylinder,  circular  base,  radius  r,  height  //, 

K'  =  (0.726  +  0.0345  /  v7)(2.43  +  0.8758  t'//). 
For  horizontal  cylinder,  radius  r, 

K'  —  2.058  +  0.0382/7-. 
For  vertical  planes,  height  //, 

K'  =  1.764  +  0.636/4^. 

Numerical  values  of  these  various  quantities  are  given  in 
tables,  Art.  46. 


64 


HEATING   AND    VENTILATING   BUILDINGS. 


46.  Total  Heat  Emitted. — The  amount  of  heat  given  off 
by  radiation  and  convection  for  various  differences  of  tempera- 
HEAT-UNITS    PER    HOUR. 


RADIATION. 

CONVECTION. 

Excess  of 
Temperature. 

Total  Radiation. 

Per  Degree  Differ- 
ence. 

Total. 

Per  Degree  Dif- 
ference. 

Deg. 
Cent. 

Deg. 
Fahr. 

Calories 
per  Sq. 
Metre. 

B.  T.  U. 
per 

Sq.  Ft. 

Calories 
per  Sq. 
Metre. 

B.  T.  U. 
per 
Sq.  Ft. 

Calories 
per 
Sq.  Metre 

B.T.U. 
per 
Sq.  Ft. 

Calories 
per  Sq. 
Metre. 

B.T.U. 
per 
Sq.  Ft. 

10 

18 

II.  2  /If 

4.1  AT 

.12  AT 

.228/T 

9-4  K' 

3.4  K'  0.94  K' 

.189  K' 

20 

36 

23.2 

8.6  " 

.16  " 

.239  " 

22.2 

8.2      " 

.11     ' 

.228    " 

3° 

54 

36.1 

13.2  " 

.20    " 

•243  " 

36.6 

13-5    " 

.22       ' 

.025    " 

40 

72 

50.1 

18.5 

•25    " 

•257 

52.  2  t 

{ 

19.2 

•30       ' 

-265    " 

5° 

9° 

65.3 

24.2 

•3*    " 

.269  " 

68.6 

25-3    " 

•37     ' 

.284    " 

60 

108 

8l.7 

30.2 

-36    " 

.281  " 

86.0 

31-8    " 

•43 

•295    " 

70 

126 

99-3 

36.6 

.42    " 

.291  " 

104.0 

38-4    " 

•49     ' 

-306    " 

80 

144 

118.5 

43-7 

.48    " 

•304  " 

122.6 

45-o    " 

•  53    " 

•3" 

90 

162 

138.7 

51.2 

-54    " 

•  317 

141.7 

52.2 

•57    ' 

•32      ' 

100 

180 

161.3 

59.5 

.6l    " 

-33     " 

161.5 

59-5    " 

.61    " 

•33      ' 

no 

198 

185-3 

68.5 

.69    " 

•035  " 

I8l.5 

67.0 

-64    " 

•334    ' 

120 

216 

211.  3 

78.0 

.76    " 

.361   " 

202. 

75-5    " 

.68    " 

•345 

I30 

234 

239.3 

88.3 

•83      ' 

•377  " 

223. 

82.2    " 

.72     ' 

•35      ' 

I40 

252 

269.5 

99-o 

.92      ' 

•395  '' 

244. 

90.0    " 

•74     ' 

•355 

ISO 

270 

302.1 

112 

.01      ' 

.416  " 

266. 

98.0    " 

.76     ' 

•36      " 

160 

288 

339-0 

125 

.  12      ' 

•435 

288. 

106      " 

•79     ' 

.365    " 

170 

306 

37'-4 

T39 

.22      ' 

•454 

310. 

115      " 

.82     ' 

•372 

1  80 

324 

418.5 

155 

•32    " 

.478     ' 

333- 

123      " 

-85     ' 

•38       " 

190 

342 

463.2 

172 

•43  J* 

•503    ' 

356. 

132      " 

.87     ' 

.384    " 

200 

360 

5"-  2 

188 

•523 

379- 

140      ' 

.89     ' 

•39      ' 

210 

378 

563-1 

208 

.68  " 

•553 

402.9 

149      ' 

.01 

•394 

220 

396 

619.0 

229 

.81  " 

•573  " 

426.7 

»57      " 

•93     ' 

.40      ' 

230 

414 

679-5' 

255 

•95  " 

.617  " 

450.4 

166      " 

•95 

•4°3    ' 

240 

432 

744.8 

275 

3.10  " 

-665  " 

475-o 

J75      ' 

•97 

.406    " 

250 

450 

848.7 

3M 

3-39  " 

.700  " 

498.6 

184      " 

•99    " 

.408    " 

FACTOR   TO   DETERMINE    RADIATION    LOSS    FROM   VARIOUS 

SURFACES. 
VALUE  OF  COEFFICIENT  K. 


Polished  silver           ...    . 

O   43 

Powdered  wood 

.    3    ^"3 

"          charcoal  

.    3.42 

.  o.2<;8 

.   q.62 

Gilded  paper  .... 

O    2"? 

a    71 

Red  copper  

...       o  16 

Paper 

.     3.71 

Zinc  

Soot    

4.OI 

Tin  

o  215 

Building  stone 

.    3    6O 

Polished  sheet  iron  

O   4^ 

Plaster                             .  .    . 

.    3.60 

Sheet  lead  

Wood           

3  .  60 

Calico  

3.65 

Rusty  sheet  iron  

1  16 

Woollens      

q.68 

Cast  iron,  new  

.     ^17 

Silk       .           

3.71 

Rusty  cast  iron  

.   l.lb 

Water  

5.31 

Glass  

Oil                    

.   7.24 

Powdered  chalk  

NOTE. — To  find  the  total  heat  emitted  by  radiation,  multiply  the  value  of  K 
as  given  in  the  above  table  by  the  numbers  corresponding  to  radiation  due  to 
difference  of  temperature  as  in  the  preceding  table. 


HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES.        65 


ture  and  from  any  surface  when  K  or  K'  is  unity  is  given  in  the 
first  table  on  p.  64,  as  computed  from  Peclet's  experiments. 
The  total  heat  emitted  by  any  surface  will  be  obtained  by 
multiplying  the  results  given  in  the  first  table  by  the  factor 
of  radiation  and  convection  for  the  required  conditions.  This 
table  is  exact  for  the  surrounding  air  at  15°  Centigrade  or  59° 
Fahrenheit. 

FACTOR   TO    DETERMINE   CONVECTION   LOSS  FROM  BODIES  OF 

VARIOUS  DIMENSIONS. 
VALUE  OF  COEFFICIENT  K'. 


Diameter. 

o. 

C/3 

Horizontal 
Cylinder. 

Vertical  Cylinder,  Height  in  Metres  and  Feet. 

Metres. 

Indies. 

0.5   m. 
1.64  ft. 

i      m. 
3.28  ft. 

h 

2      m. 

6.56  ft. 

k 
3       m. 
9.84  It. 

h 
4       m. 

13.    I2ft. 

h 

5     m. 
16.4  ft. 

h 
10     m. 
32.8  ft. 

O.O25 
0.05 
0.10 
O.2O 
0.40 
0.60 
0.8 

O.  IO 

0.16 

0.984 
1.968 
3-94 
7  -.88 
'5-74 
23.62 
31.50 
39.38 
63.0 

5.114 

6-9 
4.33 
3-o8 
2-43 

2.IO 

3-59 
2.82 
2.44 
2.25 
2.18 
2.15 

3-55 
3-22 
3-05 
2-93 
2.88 
2.85 
2.83 

3-2 

2-9 

2-75 
2.65 
2.60 
2-57 
2-55 

2.95 
2.68 
2.54 
2-45 
2.40 
2.37 
2.36 

2.84 
2.57 
2.44 

2.35 
2.31 
2.28 
2.26 

2.79 
2.52 

2-39 
2.30 
2.26 
2.23 

2.22 

2.73 
2.48 

2-35 
2.26 
2.22 
2.20 
2.18 

2.62 
2.38 
2.26 
2.17 
2.13 
2.  II 
2.O9 

1.94 

ratio  — 
d 

20 

20 

20 

15 

i3i 

12.5 

20 

The  table  on  p.  66  gives  the  total  loss  from  various  forms 
of  direct  radiating  surfaces  in  still  air,  calculated  by  Peclet's 
coefficients,  slightly  modified  by  recent  experiments. 

The  loss  of  effective  surface  due  to  rays  of  radiant  heat  im- 
pinging on  hot  surfaces  can  be  calculated  as  follows : 


FIG.  24. 


D    ()    ()    () 


FIG.  25. 


66 


HEATING   AND    VENTILATING   BUILDINGS. 


Thus  in  Fig.  24,  supposing   pipes  equally  hot,  occupying 
the  relative  positions  of  C  and  B,  the  effective  radiating  sur- 


FIG.  26. 

face  of  C  will  be  diminished  by  that  portion   of  the  circumfer- 
ence intercepted  by  the  lines  CD  and  CE.     The  angle  DCB 

HEAT-UNITS    EMITTED    PER  HOUR    PER    SQUARE    FOOT    FROM 
VARIOUS  SURFACES,  DIRECT  RADIATION,  STILL  AIR. 


Coefficient  or  Amount  per  Degree 
Difference  of  Temperature. 

Total  per  Square  Foot  per  Hour.* 

Differ- 

Horizontal  Pipe,  Diameter. 

Horizontal  Pipe,  Diameter. 

of 

6  in. 

4  in. 

2  in. 

i  in. 

6  in. 

4  in. 

2  in. 

J  in. 

Tempera- 
ture. 

Radiator,  Height. 

Radiator,  Height. 

Deg.  F. 

40  in. 
Massed 
Surface. 

40  in. 
Thin. 

24  in. 
Massed. 

12  in. 
Thin. 

40  in. 
Massed 
Surface. 

40  in. 
Thin. 

24   in. 
Massed. 

12   in. 
Thin. 

10 

0-55 

O.62 

0.66 

0.85 

5.50 

6-7 

6.6 

8-5 

2O 

.11 

•25 

•32 

1.72 

20.2 

24.9 

26.4 

34-4 

30 

.18 

•34 

.42 

1.84 

35 

39-7 

42.7 

55-2 

40 

.24 

.40 

.       .48 

1.92 

49.6 

56.2 

59-° 

77 

50 

.29 

.46 

•54 

2.  or 

64.5 

73  o 

77 

100 

60 

•33 

•50 

•58 

2.06 

79.8 

90 

95 

124 

70 

•36 

•54 

•63 

2.  12 

95.2 

1  08 

148 

80 

.40 

•58 

•67 

2.18 

112 

127 

133 

90 

•43 

.63 

.72 

2.24 

128 

147 

153 

199 

100 

•47 

.66 

•  76 

2.28 

147 

167 

175 

228 

IIO 

.51 

.71 

.80 

2-34 

1  66 

1  88 

198 

257 

120 

•54 

1.74 

•  84 

2-39 

184 

208 

219 

287 

130 

•57 

1.78 

.88 

2-44 

203 

230 

242 

I4O 

.61 

1.81 

.91 

2.48 

223 

2=12 

266 

346 

150 

.64 

1.84 

•94 

2-53 

244 

276 

291 

378 

160 

.66 

1.87 

•97 

2-57 

265 

300 

316 

410 

170 

.69 

1.91 

2.  02 

2.62 

286 

324 

341 

•    443 

i  So 

•  72 

1.94 

2.05 

2.65 

307 

348 

367 

475 

190 

•75 

1.98 

2.09 

2.71 

330 

375 

393 

512 

200 

.78 

2.OI 

2.  12 

2.76 

356 

403 

415 

552 

225 

•87 

2.12 

2.24 

2.91 

420 

477 

500 

650 

250 

•97 

2.23 

2-35 

3.06 

493 

557 

587 

762 

275 

2.07 

2-34 

2-47 

3-22 

563 

637 

670 

872 

300 

2.17 

2-45 

2.58 

3-37 

654 

742 

780 

IO2O 

325 

2.27 

2-55 

2    70 

3.50 

740 

840 

882 

II5O 

350 

2-37 

2.67 

2.82 

3.66 

835 

945 

995 

1295 

*  Results  divided  by  loco  give  approximate  weight  of  steam  condensed  per 
hour. 


HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES.        67 

has  for  its  sine  DB/BC.  DB  is  the  external  radius  of  the 
pipes,  BC  the  distance  between  the  centres,  which  is  usually 
not  far  from  two  diameters.  In  Figs.  25,  26,  and  27  the  shaded 


FIG.  27. 

areas  show  the  position  of  surface,  by  which  the  radiant  heat 
coming  from  a  single  pipe  or  a  single  section  is  intercepted 
and  reradiated  to  its  source. 

Supposing  the  distance  apart  to  be  as  given  above,  the  fol- 
lowing table  gives  the  percentage  of  reduction  in  amount  of 
heat  transmitted  due  to  this  cause  : 


Number    of 
Rows  of 
Tubes. 

Amount  of  Surface 
from  which  no  Radi- 
ation takes  place. 

Probable  Reduc- 
tion in  Heat 
transmitted. 

Per  cent. 

Per   cent. 

I 

16 

8 

2 

42.7 

21.3 

3 
4 

6 

55 
66 

73 
79 

27-5 
33 
36.5 
39-5 

47.  Material  of  Radiators.* — As  bearing  directly  upon 
the  above  subjects,  the  writer  planned  a  series  of  experiments 
which  were  conducted  by  E.  T.  Adams  and  M.  H.  Gerry  in 
Sibley  College  during  the  winter  of  1893-4.  The  results  of 
these  experiments  show  that  the  amount  of  heat  transmitted 
does  not  depend  so  much  upon  the  kind  of  metal  as  upon  the 


*  Transactions  of  American  Society  Heating  and  Ventilating  Engineers,  vol.  i. 


68 


HEATING   AND    VENTILATING   BUILDINGS. 


media  in  contact  with  the  metal  on  both  sides.  The  experi- 
ments performed  were  quite  elaborate 
ones,  and  every  precaution  was  taken 
to  secure  accuracy. 

The  heat  measurements  were  made 
with  an  apparatus  arranged  as  in  Fig. 
28.  The  box  A  was  fitted  so  that 
plates  of  cast  or  wrought  iron  of  vari- 
ous thickness  could  be  used  as  a  bot- 
tom. The  box  B  directly  beneath  the 
box  A  was  so  constructed  that  steam, 
air,  oil,  or  water  of  a  given  tempera- 
ture could  be  supplied,  and  would  transmit  its  heat  upward 
through  the  bottom  of  the  box  A.  The  heat  thus  transmitted 
was  measured  by  its  effect  on  the  temperature  of  the  water  in 
box  A.  The  results  were  reduced  to  thermal  units  passing 
through  one  square  foot  of  metal  per  hour,  for  each  degree 
difference  in  temperature  in  box  B  and  box  A. 

We  see  from  the  table  that  when  steam  and  water  are  in 
contact  with  the  plates  considerable  difference  in  the  results 
were  obtained  by  varying  the  thickness  of  the  plate  in  the  bot- 
tom of  the  vessel  A.  But  when  air  is  on  one  side,  the  results 
are  little  affected  by  varying  the  nature  and  thickness  of  the 
plate.  The  experiments  were  made  with  a  clean  cast-iron 
plate,  also  with  a  wrought-iron  plate,  and  then  with  each  of 
these  plates  covered  with  a  thick  layer  of  boiler-scale,  neatly 
fitted.  In  the  latter  case  the  heat  had  to  pass  through  both 
the  scale  and  the  plate. 

Tne  table  (page  69)  is  of  interest,  since  it  shows  that  with 
the  same  material  for  heat  transmission,  and  with  the  same  dif- 
ference of  temperature,  there  is  a  great  difference  in  the  results. 
These  depend  more  upon  the  material  which  receives  or  takes 
up  heat  than  upon  the  material  which  conducts  it.  It  can  be 
readily  seen,  however,  that  such  would  not  -have  been  the  case 
with  poor  conductors. 

Thus  the  heat  transmission  through  iron,  from  steam  to 
water,  varies  from  25  to  75  times  as  much  as  that  transmitted 
through  the  same  plate  from  air  to  water.  When  the  heat 
was  passing  from  steam  to  water  there  was  a  sensible  differ. 


HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES.        69 


cnce,  due  to  the  material  and  thickness  of  the  plates  used, 
but  when  passing  from  air  to  water  this  difference  wholly  dis- 
appeared. In  passing  from  steam  to  water  the  rate  of  trans- 
mission increased  very  rapidly  with  increase  in  difference  of 
temperature. 

HEAT  TRANSMITTED  IN  THERMAL  UNITS  FOR  EACH  SQUARE 
FOOT  PER  HOUR  AND  PER  DEGREE  DIFFERENCE  OF  TEM- 
PERATURE. 


Difference 

Steam  to  Water. 

Lard  Oil  to 
Water. 

Air  to  Water. 

ol  Tem~ 
perature  of 
the  Two 
Sides  of  the 
Plate, 
Deg    Fahr. 

Clean 
Wrought 
Iron  T5B  inch 
thick. 

Clean 
Cast 
Iron  TTB 
inch 
thick. 

Wrought- 
iron  Plate 
and  Scale 
iJ4  inches 
thick. 

Cast-iron 
Plate  and 
Scale  ,9fi 
inches 

thick. 

Clean 
Cast- 
iron 
Plate 

h  inch 
thick. 

Cast- 
iron 
Plate 
and 
Scale. 

Clean 
Cast  Iron 
/.inch 
thick. 

Cast- 
iron 
Plate 
and 
Scale. 

25 

28.8 

21 

2.7 

1.8 

6.5 

4 

1.2 

0.15 

50 

6o.O 

48 

5-5 

3-6 

13 

8 

2-5 

0-3 

75 

96.0 

84 

8.2 

5-4 

19.5 

12 

3-7 

o.45 

100 

150.0 

127 

II 

7-3 

26 

16 

5 

0.6 

125 

228 

185 

13.7 

9.1 

3L5 

20 

6.2 

o.75 

150 

348 

255 

16.5 

10.9 

39 

24 

7-5 

0.9 

175 

19.2 

12.7 

45-5 

28 

8.7 

1.05 

2OO 

22 

14.6 

52 

32 

10 

1.2 

300 

33 

21.9 

78 

48 

15 

2.8 

400 

44 

36.2 

20 

2.4 

500 

25 

3.0 

600 

3-6 

48.  Methods  of  Testing  Radiators. — So  far  as  the  writer 
knows,  no  standard  method  has  been  adopted  for  use  in  the 
testing  of  radiators,  and  while  numerous  tests  have  been  made 
by  different  engineers  and  experimenters,  they  are  often  not 
concordant  either  as  to  the  method  of  testing  or  as  to  the  re- 
sults obtained.  The  results  in  the  testing  of  radiators  are 
greatly  affected  by  small  variations  in  temperature,  by  irregu- 
lar air-currents,  and  by  the  amount  of  moisture  contained 
originally  in  the  steam.  Obscure  conditions  of  little  apparent 
importance  and  often  disregarded  greatly  influence  the  results. 
The  heat  emitted  _by  the  radiator  is  in  all  cases  to  be  computed 
by  taking  the  difference  between  that  received  and  that  dis- 
charged. This  result  is  accurate,  and  easily  obtained.  This 
heat  is  utilized  in  warming  the  air  and  objects  in  the  room, 
and  to  supply  losses  from  various  causes,  which  take  place 
constantly,  and  is  diffused  so  rapidly,  and  used  in  so  many 


70  HEATING   AND    VENTILATING   BUILDINGS. 

ways,  that  it  is  practically  impossible  to  measure  it,  although 
it  is,  of  course,  equal  to  that  which  passes  through  the  radiator. 
The  radiating  surface  is  almost  invariably  heated  either  by 
steam  or  by  hot  water.  In  the  case  of  a  steam  radiator  the 
heat  received  may  be  determined,  by  ascertaining  the  number  of 
pounds  of  dry  steam  condensed  in  a  given  time,  multiplying 
this  by  the  heat  contained  in  one  pound  of  steam,  and  deduct- 
ing from  this  product  the  weight  of  condensed  water,  multi- 
plied by  its  temperature.  To  make  a  test  of  this  kind  with 
accuracy  requires,  first,  a  knowledge  of  the  amount  of  moisture 
contained  in  the  original  steam  ;  second,  the  pressure  of  the 
steam  or  its  temperature;  third,  an  arrangement  for  permitting 


FIG.  29.— RADIATORS  ARRANGED  FOR  TESTING. 

water  of  condensation  to  escape  from  the  radiator  without  the 
loss  of  steam,  and  means  of  accurately  weighing  this  water, 
and  also  of  determining  its  temperature.  The  radiator  can  be 
located  in  any  desired  position  in  the  room;  on  the  floor, 
or  slightly  elevated  therefrom.  The  temperature  of  the  room 
during  the  test  should  be  maintained  as  nearly  constant  as 
possible,  and  no  test  should  be  less  than  from  3  to  5  hours  in 
length.  The  method  adopted  by  Mr.  George  H.  Barrus  in 
making  a  radiator  test  is  shown  in  Fig.  29.  The  one  adopted 
by  the  author,  in  many  respects  similar,  is  shown  in  Fig.  30. 

In   some   recent  tests  of   steam  radiators   made  at  Sibley 
College  *  the  author  adopted  the  following  plan  of   operation 

*  See  Transactions  vol.  i.,  American  Society  Heating  and  Ventilating  En 
gineers.  (^ 


HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES.        Jl 

for  measurement  of   the  heat    discharged    and   for   operating 
the  radiators : 

First,  the  steam  supplied  to  the  radiator  to  be  passed 
through  a  separator  and  a  reducing-valve  to  remove  entrained 
water  and  maintains  a  constant  pressure  during  any  given 
run.  Second,  the  amount  of  moisture  in  the  steam  to  be 
measured  by  a  calorimeter,  and  corrections  made  to  the  result 
for  the  entrained  water.  Third,  the  pressure  and  temperature 
of  the  steam  in  the  radiator  to  be  measured  by  accurate  gauges 
and  thermometers.  Fourth,  the  amount  of  heat  passing 
through  the  radiator  to  be  obtained  by  weighing  the  condensed 


FIG.  30. — RADIATOR  ARRANGED  FOR  TESTING. 

:eam,    measuring   its   temperature,    and    computing   by   this 
leans  the  heat  discharged. 

Fifth,  the  air  from  the  radiator  to  be  effectually  removed, 
irge  errors  are  caused  by  leaving  varying  amounts  of  air  in 
:he  radiator.  The  ordinary  air-valve  is  often  very  unsatisfac- 
tory for  this  purpose ;  if  used,  it  must  be  closely  watched,  or 
the  results  may  be  seriously  affected. 

The  heat  supplied  was  computed  by  knowing  the  weight, 
percentage  of  moisture,  and  the  heat  contained  in  one 
pound  of  steam.  Various  methods  were  tried  for  drawing  off 
the  condensed  water  :  in  some  tests  a  trap  was  used,  but  better 
results  were  obtained  by  employing  a  water-column  with  gauge- 
glass  and  drawing  off  the  water  of  condensation  by  hand,  at 


HEATING   AND    VENTILATING   BUILDINGS. 


such  a  rate  as  to  maintain  a  constant  level  in  the  glass.  To 
prevent  loss  by  evaporation,  this  water  needs  to  be  received 
either  into  a  vessel  containing  some  cold  water,  or  else  into  one 
with  a  tight  cover,  the  latter  being  generally  preferred. 

Methods  of  Testing  Indirect  Steam  Radiators. — For  this 
case  the  general  methods  of  testing  should  be  the  same  as 
those  previously  described,  and  in  addition  the  volume  of  air 
which  passes  over  the  radiator  should  be  measured ;  also,  its 
temperature  before  and  after  passing  the  radiator.  For  meas- 
uring the  velocity  of  air  the  most  accurate  instrument  at 
present  known  is  the  anemometer,  which  has  been  described 
and  illustrated  in  Article  30,  page  37.  In  measuring  the  veloc- 
ity the  anemometer  should  be  moved  successively  to  all  parts 
in  the  section  of  the  flue,  and  the  average  of  these  results 
should  be  used.  The  velocity  in  feet  per  minute  multiplied  by 

the  area  of  section  in  square 
feet  should  give  the  number 
of  cubic  feet.  The  number 
of  cubic  feet  of  air  heated 
can  also  be  computed,  as  ex- 
plained in  Article  30,  page  40, 
by  dividing  the  heat  emitted 
by  the  radiator  by  the  prod- 
uct of  specific  heat  of  air 
and  increase  in  temperature. 
The  heat  which  is  ab- 
sorbed by  the  air  can  be  com- 
puted by  multiplying  that 
required  to  raise  one  cubic 
foot  one  degree,  as  given  in 
Table  VIII,  by  the  total  num- 
ber of  cubic  feet  warmed  mul- 
p  APPARATUS.  tipl;ed  by  thg  ;ncrease  Jn  tgm_ 

perature.  Fig.  31  shows  an  arrangement  adopted  by  the  author 
in  testing  indirect  radiators,  the  air-supply  being  measured  by 
an  anemometer  not  shown. 

Testing  Hot-water  Radiators. — The  amount  of  heat  trans- 
mitted through  the  surfaces  of  a  hot-water  radiator  can  be 
determined  in  either  of  two  ways  :  first,  by  maintaining  circula- 


OF  THE    ^ 

XJNIVEBSITY 


HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES.        73 

tion  at  about  the  usual  rate,  measuring  the  temperature  of  the 
water  before  entering  and  after  leaving  the  radiator;  also, 
measuring  or  weighing  the  water  transmitted.  The  heat  trans- 
mitted would  be  equal  in  every  case  to  the  product  of  the  weight 
of  water,  multiplied  by  the  loss  of  temperature.  In  making 
these  tests  the  same  precautions  as  to  removing  the  air  from 
the  radiator  must  be  adopted  as  in  testing  steam  radiators. 

These  radiators  can  also  be  tested  by  filling  with  water  at 
any  desired  temperature  and  noting  the  time  required  for  the 
water  to  cool  one  or  more  degrees.  In  this  case  the  iron 
which  composes  the  radiator  would  cool  the  same  amount,  and 
a  correction  must  be  added.  The  easier  way  to  correct  for  the 
metal  composing  a  radiator  is  to  consider  the  weight  as  that  of 
the  water  increased  by  that  of  the  iron  multiplied  by  its  specific 
heat.  The  specific  heat  of  wrought  iron  is,  practically,  I  di- 
vided by  9 ;  that  of  cast  iron,  I  divided  by  8 ;  hence  for  a  cast- 
iron  radiator  the  effect  would  be  the  same  as  though  we  had 
an  additional  amount  of  water  equal  to  -J  of  the  weight  of  the 
radiator. 

In  the  practical  operation  of  this  test  the  water  in  the 
radiator  must  be  kept  thoroughly  agitated  by  some  sort  of 
stirring  device. 

49.  Measurement  of  Radiating  Surface. — The  amount 
of  radiating  surface  is  usually  expressed  in  square  feet,  and  the 
total  surface  is  that  which  is  exposed  to  the  air,  and  includes 
all  irregularities,  metallic  ornaments,  etc.,  of  the  surface. 

Where  the  surface  is  smooth  and  rectangular  or  cylindrical 
it  is  easily  measured,  but  where  it  is  covered  with  irregular 
projections  the  measurement  is  a  matter  of  some  difficulty  and 
uncertainty.  The  only  practical  method  of  measuring  irregu- 
lar surface  seems  to  be  that  of  dividing  it  up  into  small  areas 
and  measuring  each  one  of  these  areas  separately  by  using  a 
thick  sheet  of  paper  or  a  bit  of  cord,  and  carefully  pressing  it 
into  every  portion  of  the  surface.  The  sum  of  all  the  small 
areas  is  equivalent  to  the  total  area. 

This  method  is  at  best  only  approximate,  and  even  when 
exercising  the  utmost  care  different  observers  are  likely  to  differ 
three  or  four  per  cent  in  their  results.  The  writer  has  tried 
several  other  methods  of  measuring  surface,  but  so  far  without 


74  HEATING   AND    VENTILATING   BUILDINGS. 

marked  success.  One  method,  which  promised  good  results,  was 
to  cover  the  whole  surface  with  a  thin  paint  and  compare  the 
weights  with  that  required  for  covering  one  square  foot  of  plain 
surface.  This  method  proved  even  more  approximate  than  the 
other,  and  had  to  be  abandoned,  as  the  paint  was  not  of  equal 
depths  on  all  portions  of  the  surface. 

The  total  contents  of  the  radiator  in  cubic  feet  can  be  easily 
determined  by  filling  it  with  a  weighed  amount  of  water  of  a 
known  temperature  and  dividing  the  result  by  the  weight  of  one: 
cubic  foot.  The  volume  displaced  by  the  whole  radiator  can 
be  determined  by  immersing  it  in  a  tank  whose  cubic  contents, 
can  readily  be  measured.  The  difference  between  the  cubic 
contents  when  the  radiator  is  in  the  tank  and  when  taken  out 
is  the  volume  of  the  radiator.  For  this  test  the  openings  in; 
the  radiator  must  be  tightly  stopped. 

The  same  method  applied  with  the  radiator  immersed  ini 
both  cases  ;  but  in  one  case  with  the  radiator  filled  with  air  and 
the  other  with  water  would  give  as  a  result  the  water  displaced' 
by  the  metal  actually  used  in  the  construction,  or,  in  other 
words,  the  cubic  volume  of  the  metal.  This  could  no  doubt 
be  more  accurately  obtained  by  dividing  the  weight  of  the 
metal  by  the  weight  of  one  cubic  inch  or  cubic  foot.  These 
methods  give  accurate  means  of  measuring  the  total  external 
and  internal  volume  of  the  radiator,  but  not  the  surface. 

50.  Effect  of  Painting  Radiating  Surfaces. — In  the  ex- 
periments of  Peclet  which  have  been  given  in  Article  46  the  effect 
of  different  surfaces  has  been  fully  considered.  From  these 
experiments  it  would  appear  in  a  general  way  that  the  char- 
acter of  the  surface  affects  the  heat  given  off  by  radiation 
only,  and  not  that  given  off  by  convection.  In  ordinary  cases 
of  direct  radiation,  because  the  surfaces  are  closely  massed  to- 
gether, the  radiant  heat  does  not  probably  exceed  on  an  aver- 
age 40$  of  the  total  emitted,  and  is  nothing  in  indirect  heating. 
From  the  experiments  quoted,  on  page  64,  it  would  appear  that 
if  we  consider  the  radiant  heat  given  off  as  100  from  a  new  sur--j 
face  of  cast  iron,  that  from  wrought  iron  would  be  87,  from  a 
surface  coated  with  soot  or  lampblack  125,  from  a  surface  with 
a  lustre  like  new  sheet  lead  20^,  from  a  polished  silver  surface  ! 
13^.  These  results  make  very  much  less  difference,  when  ap- 


HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES.        75 

plied  to  total  heat  emitted,  since  the  total  radiant  heat  is  only  a 
small  portion  of  the  whole  heat  given  off.  Calling  the  radiant 
heat  as  40$  of  the  total,  we  should  have  the  following  numbers 
as  representing  the  heat  emitted  from  various  surfaces : 

Cast  iron,  new 100     Rusty  surface 102 

Wrought  iron.    .......     93     Bright  iron  surface 72 

Dull  lampblack 106     White  lead,  dull 106 

The  writer  had  some  experiments  made  in  Sibley  College, 
the  results  of  which  showed  that  the  effect  of  painting  was  to 
increase  the  amount  of  heat  given  off. 

It  was  found  that  two  coats  of  black  asphaltum  paint 
increased  the  amount  6$,  two  coats  of  white  lead  9%.  Rough 
bronzing  gave  about  the  same  results  as  black  paint. 

On  the  other  hand  a  coat  of  glossy  white  paint  reduced  the 
amount  of  heat  emitted  about  io#. 

51.  Results  of  Tests  of  Radiating  Surface.— The  results 
of  the  experiments  of  Peclet  have  been  given  quite  fully,  and 
they  will  be  found  to  agree  well  with  best  modern  tests  when 
the  conditions  are  similar.  The  radiating  surface  ordinarily 
employed  for  steam  or  hot-water  heating  consists  of  a  number 
of  pipes  closely  grouped  together  so  as  to  occupy  as  little 
space  as  possible.  In  some  instances  long  coils  or  series  of 
parallel  rows  of  pipe  are  employed  arranged  horizontally,  but 
ordinarily  the  pipes  are  vertical,  and  grouped  together  in  two 
to  four  rows.  The  usual  height  of  radiator  is  36  to  40  inches 
with  the  bottom  placed  about  3  inches  from  the  floor,  making 
the  actual  height  of  radiating  surface  about  3  feet.  In  some 
instances  radiators  are  lower,  in  which  case  the  results  per  unit 
of  surface  are  considerably  increased. 

The  value  of  a  radiator  in  which  the  surface  is  grouped  so 
as  to  prevent  the  free  escape  of  radiant  heat  will  depend  largely 
upon  the  effectiveness  with  which  the  air-currents  strike  the 
heating  surfaces.  There  is  a  tendency  for  heated  air  to  move 
in  a  vertical  current  in  contact  with  the  radiator  surface,  and 
thus  to  keep  the  upper  portion  in  a  very  hot  atmosphere,  which 
has  the  effect  of  materially  lessening  its  efficiency.  The  prac- 
tical effect  of  these  restrictions  is  to  reduce  the  heating  power 
of  radiators  which  are  composed  of  a  large  amount  of  surface 


HEATING   AND    VENTILATING   BUILDINGS. 


closely  grouped.  The  following  summary  of  a  series  of  radi- 
ator tests  made  by  J.  H.  Mills  shows  that  with  very  small 
radiators  the  results  are  in  practical  accordance  with  those  of 
Peclet's  experiments,  but  as  the  radiators  increase  in  size  they 
fall  off  about  in  proportion  to  the  loss  of  effective  radiat- 
ing surface. 


B.  T.  U.  per  Sq.  Ft.  per  Hour  per  Degree 
Difference  of  Temperature. 

Sq.  Ft.  of  Radiating 
Surface. 

Difference  of 
Temperature. 

Peclet's  Formula. 

Actu-il 

10 

155 

.66 

2.  JO 

20 

150 

.84 

2.08 

30 

I58 

.87 

2.06 

40 

175 

.92 

1-75 

50 

155 

.86 

1-73 

60 

165 

1.89 

1.67 

The  following  experiments  were  made  by  Tredgold  *  for 
the  time  of  cooling  of  water  in  vessels  of  various  kinds.  The 
writer  has  reduced  the  results  to  heat-units  given  off  per  square 
foot  of  surface  per  hour. 

SUMMARY   OF   TREDGOLD'S    EXPERIMENTS. 


"o 

'o 
o 

o£ 

Heat-units  Emitted  per  Sq. 

3-0* 

3 

Ft.  per  Hour. 

•tLjr     ,         •     j 

*-*  o 

y   h 

Cooling. 

Material  of  Radiator. 

i- 

|f 

1* 

Total 

Per 

By 

J* 

1* 

i£ 

Q 

Heat- 
units. 

Deg.  Diff  . 
Temp. 

Pe'clet's 
Formula. 

Hot  water... 

Tinned  iron  cylinder.  .  .  . 

180 

55-5 

124.5 

255 

-43 

1.17 

Hot  water..  . 

Glass 

1  80 

56.5 

426 

2.37. 

2    ^6 

Wrought-iron  block  
Rusty  wrought  iron  

1  80 
180 

57 
57 

123 
123 

434 
486 

2.41 
2.70 

2-5 

Prof.  C.  L.  Norton,  Boston,  Mass.,  reported  in  Transactions 
of  American  Society  of  Mechanical  Engineers,  1898,  that  the 
heat  transmitted  from  a  body  of  hot  oil  was  proportional  to 
the  following  numbers : 


tfew  pipe  100 

Painted  dull  white   115 

Coated  with  cylin- 

Fair condition      .    .   115 

Painted  glossy  "      1004 

der  oil  1  16 

Rusty  and  black  ....   1  18 
Cleaned  with  caustic 

Cleaned  with  pot- 
ash                           US 

Painted  dull  black  120.5 
Painted  glossy  '*      101 

potash  118 

*  Tredgold's  Warming  and  Ventilating  of  Buildings,  second  edition,  pages 
56  to  60. 


HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES.         J? 

The  following   table  is  abstracted  from  one  published   in 
"  Warming  and  Ventilation  of  Buildings,"  by  J.  H.  Mills: 


•jiy  PUB  mea^s 
•ma     aaoSaa 

_#*3-    S^SS.^2^ 

'S^S  S'Kvg^  ?JcS  S\£R£I?#S8 

J3Q     S?IUn-JB9H 

UH  Jad  -jj  'bs 
jad  pasuapuo3 

fc;;H  jt^l^Hs? 

WCI         M«O^^OSfOO*        lAO*^  O^*O    m  Iv 
M    x    O">OM\O    M\O    *  H    M    K  M  <A    O\  ir.  t~~.  * 
fOfOfOM^W    N    COfON    rr>M    ««    H  Si   (i)  |9) 

J31BM    jo     -sqT 

*8° 

p5-5-5-    5-  5-  5-  5-  5-  5-  5-  5- 

S.'iS.vS  S  #£3  ^^'S.^^-vS1  5;^  S^-5, 

5gJ[ 

-i 
"~ 

1    -1 

s            * 

0 

URRR    RRg.RRg.Rg. 

RR3§vSv£££  f:R?.R^^SRKRR 

H 

e 

N  *i2  S,  S,^  ^'iS  "2  'S  ^2  °°  &°°  °°  °°  °°  °°  °° 

1 

e.NN     .88SSSS8 

*30BUnC 

&88    <£-R83Rr&8 

888888888888888888 

jo   Wji    aasnbs 

<!  m-i--*     co  6  0>  -»•  6  •*  •«•  ~ 

(1)                                 M                    M    »*    •«$•   N 

:  :  :  :^  :  .  .        ... 

i  1  1  :3  :  :  ':        1  i  i 
i  ".  i  ;-    '.'..        '.'.'. 

:  :  :  :  a  :  :  6  u    :  :  : 

jn>o  10  o  0  N  oo^  o  t^oo^  in  o^  o^oo  vo^  O^  O  ^> 

!  fl 

i  •  ;»-  is  9  ••• 

ffi   11 

:  •  :§M     :£  2    '•  :  • 

•  :    -5  o      "S  -a 
:«  •  :u-      -rt  S 

:::::::  fc  s    :&•::::; 

i  i  :  i  :  i  i  a       :  §  i  i  i  i  i  : 
:  2*^  :r  :::::: 

Description  of  heating  surface  
Plain  wrought-iron  pipe,  i",  100'  in  a  single  horizontal  lir 
Plain  cast-iron  pipe  3''  diameter  outside,  5'  long  
"  3"  "  5'  "  but  thinne 
Ribbed  cast-iron  pipe,  S.  Williams;  core  3"  in  diam.,  5' 
cylinders,  i"  cylinders  '  
Ribbed  cast-iron  pipe,  No.  i,  J.  Nason  &  Co.,  3"  outside.  . 

RibSed38  -ir°n  ^  J"  Na'°n  *  C"  '  }  Placed  «ide  bv  8ideC 
Curved  rib  cast-iron  radiator,  Morris,  Tasker  &  Co  
Box-radiator,  cast  iron,  with  straight  vertical  ribs  
k  Vertical  cast-iron  ringed-pipe  radiator,  7  Sec.  "  Clogston  ' 

Cast-iron  pipe  3"  diam.,  in  single  line.  

Steel  pipe  4"  diam.,  in  single  line  
Brass  i"  horizontal  pipe  ;  4-branch  circulation  
Wrought-iron,  i"  horizontal  pipe,  4-branch  circulation  .. 
Plain  brass  vertical  tube-radiator  ±"  diam.,  2x4  
Corrugated  brass  vertical  tube-radiator  |"  diam.,  2  x  16.. 
Vertical  wrouglit-iron  tube-radiator,  Walworth,  i  row  of 
a  "  •» 

"  Union  "  radiator,  cast  iron,  6  sec.,  29"  high  
"Triumph"  r.idiator,  A.  A.  Griffing  Iron  Co.,  cast-iron,  i 
Peirce  Excelsior  "  cast-iron  radiator,  10  sections  
"  Art  M  radiator,  cast  iron,  6  panels  
4  xa  "  double  
Detroit  Radiator  Exeter  Machine  Co.,  cast-iron,  8  loops.. 
Single  bar  of  Gold's  Pin  Indirect  Radiator,  3"  x  6"  x  3!'.  .  . 
Howard  Oxbow  Radiator,  2  loops,  cast  iron.  Date  1866.. 

•2931  'UOSBN  *H  'f 

•888»  'SUFW  'H  'f 

HEATING   AND    VENTILATING   BUILDINGS. 


The  following  table  gives  the  abstract  of  a  large  number  of 
radiator  tests  made  under  the  supervision  of  the  author:  * 


Name  or  Kind  of  Radiator. 

Dimensions. 

Tests  of 
Kelsey  & 
Jackson. 

Tests  of 
Camp  & 
Woodward. 

Tests  of 
Dunn  & 
Mack. 

a 

V 

£ 

1 

& 

*<u 

I 

.81 
.81 

.78 
.78 

•77 

•79 
.81 
.82 
.87 
.82 
.82 
.87 
.81 
.81 
.86 
•85 
-85 
.87 
.85 
.86 
.91 

:SJ 

.78 
-83 

•79 
.87 

1.82 
.86 
.89 
•83 
.81 
.89 

.86 
1.87 
.86 
•  85 

•9o 
.87 
.86 
-85 
.88 
•S3 
.89 
•  83 

No.  Sections. 

Rows  of  Tubes. 

£ 
% 
rf 

rt 
3 

cn 

1 
y 

C 

"OJD 

'5 
E 

„  i  Difference  oi 
•&*§£  Temperature, 
bx  1  Deg.  Fahr. 

Coefficient. 

Difference  of 
Temperature, 
Deg.  Fahr. 

MM*  1 

ffff-3  1  Coefficient- 

b 

££ 
*$ 

jgQ 

Q 

Coefficient. 

W.  I.  vertical  pipes  
W.  I.  vertical  pipes,  Nason  

W.  I.  hot  water,  Western  No.  2.  . 
W.  I.  steam,  Western  No.  2  
Steel,  hot  water,  Western  No.  i  .  . 

12 

16 

12 
12 
12 

4 
3 

4 
4 

,\ 

53-6 
47-94 

41.19 

43-33 

45.  T3 

3» 
36 

32i 
32* 

35 

1.62 

1.669 
1.83 

M5 
144 

X33 

:::::: 

133- 

i3o. 

137- 
144. 
i48. 
158. 
i46. 
147.6 
159-5 
144.6 
143-0 
155.0 
153-2 
154.4 
159-4 
153-1 
157-1 
171  .1 

!6i 

-56 
.60 
.81 
.68 
•79 
.60 

•79 
-95 
•59 
•50 
•55 
.76 
•14 
.02 
.88 

^J 

:S 

.88 
.46 
37 
•75 

i-77 

-59 
.80 
•59 
-51 
•7i 

•73 
.70 
•74 
.91 
.01 
•99 
•67 

:3 

:^e 

•45 

3-3 
3-7 
4-3 
4-3 
5-5 
5-7 
5-8 







Steel  steam  Western  No.  i  . 

\& 

10 

9 

3 

3 

79 
41.8 

48    7 

% 

149 

1.64 

"       "      Bundy  filite  

"      Reed 

151 
147 
136 
151 
139 
130 

1.688 
i  .627 
!-523 
1.688 
1-565 
1.582 

;;;;•; 

15° 
137-5 
157 
153 
152 
159 

147.0 
156.3 
166.5 
151-5 
145-4 
165.6 

155.3 
158.7 

*55-i 

'Sf-s 

167.6 
158.4 
154 
153 
160 
152.6 
164.3 
151  .0 

'55-6 
167.1 
194-5 
213.2 
151  -9 
»6j 
182.4 

"       "      Royal  Union  

II 

26 
13 

12 
IO 

1C 
IO 

10 

IO 

3 

3 
3 

i 
t 

2 

I 
I 

I 
I 

I 
I 

49.12 
52.8l 

49-9 
48-17 
40.2 

48 
40 

40 
40 

38.65 
58.2 

37 
17 

37* 
37* 

37 

38 

38 
38 
30 

151 

2.08 

*'       "      Perfection  Steam  

*4       "      Perfection  Hot  Water. 
"       "      Ideal  Steam  

91 

1.63 

147.8 
H7 
144 

r-456 
1-374 
1-433 

89 
150 

1.664 
I-55 

"       "         "     Hot  Water  
"       "      National  Steam  

140 

1.61 

"       "      Whittier  Ex.  Surface.. 
**       '*      Michigan  Indirect  
2-inch  pipe,  single,  horizontal...  . 

142 

9i 
140 

»-«3 

T-434 
1.27 



i-inch  pipe,  single,  horizontal.,  .  . 

Vol. 
fcineers. 


Transactions    American    Society   Heating    and    Ventilating    En- 


HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES. 


79 


fESTS  OF  RADIATORS 
FORM  AIR -FLUES, 
RADIATORS.* 


WITH    EXTENDED   SURFACE   SO    AS   TO 
COMPARED    WITH     PLAIN    CAST-IRON 


u 

a 

C 

Tempera- 

ICT 

fcj 

1 

-' 

5 

O 

ture. 

C 

Q 

^    U 

^ 

Q. 

J 

£u 

3 

4 

K 

•§s. 

o 

u 

S 

u 

Description  of 
Radiator. 

umber  of 

o 

~.  •; 

11 

"o 

58 
2-S 

9 

C/5 

| 

cam-press 

a 

V 

8 

ifference. 

§i^' 

2£_l 
c/5  «-   r 
-ofe 

|| 

M 

ft 

•° 

£ 

EC 

1/3 

in 

06 

Q 

p 

Q 

CQ 

- 

CQ 

i 

2 

3 

4 

5 

6 

7 

8 

9 

10 

ii 

12 

13 

A    1  Extended  surf  ace, 

Joy  flue.  
n          Do.      do.      do. 

9 

i 

37 
37 

8f 
8f 

57.8 
6.40 

3.96 
4.0 

225 
226 

52-1 
67.6 

173 
158 

3.12 
0.332 

0.00170 

O  .  OO2  1  2 

1.65 

2.05 

302 
323 

312 

3" 

A  '    Same  as  A  with  flues 

• 

9 

37 

84 

40.4    3.9 

224 

S7.8 

172 

0.329      O.OOIQ7 

i  .97 

3T8 

-788 

a'          Do.      do.      do. 

i 

37 

8f 

4.243.9 

224 

70-5 

154 

0-379 

0.00247 

2-39 

369 

288 

B     Crescent  Flue  Radia- 

!     lor  

9 

^64 

gs. 

60.8    3.81 

223 

7?.  6 

149 

0.245 

0.00136 

1.30 

24.8 

28O 

b'          Do.      do.       do. 

i 

3°i 

8| 

6.23  4.0 

225 

68.8 

156 

0.360 

O.OO23I 

2.24 

350 

296 

C     Plain    Bundy,  single 

row  

14 

39* 

2i 

40.25  3.94 

224 

6s-  7 

is8 

0-345 

O.OO243 

2.33 

335 

312 

c1          Do.      do.      do. 

I 

39* 

2* 

2.83 

4i 

226 

66.2 

0-375 

0.00237 

2.26 

365 

312 

D    Princess    flue    radia- 

tor   

9 

38 

8* 

63.1 

3.96 

22S 

7'-S 

153 

2.21 

0.00145 

1.39 

214 

285 

d          Do.      do.      do. 

I 

38 

8* 

7.18 

4-1 

226 

70.5 

i55 

O.3OI 

O.OOI94 

i9 

292 

294 

D'    Same  as  D  with  ex- 

1     tended   surface  re- 

9 

38 

8* 

41.2 

3-97 

225 

71.7 

153 

0.292 

O.OOI9I 

i.S.s 

284 

285 

d'         moved. 

3» 

8* 

4-50 

4.0 

222 

66.2 

J59 

0.365 

0.00231 

2.24 

355 

312 

52.  Tests  of  Indirect  Heating  Surfaces. — The  tests 
which  have  been  made  on  indirect  heating  surfaces  show  very 
great  difference  in  results,  varying  from  those  given  by  Peclet 
for  the  loss  due  to  convection  alone,  to  results  which  are  8  or 
10  times  as  great.  This  difference  in  result  is  no  doubt  due  in 
each  case  to  the  velocity  of  air  which  comes  in  contact  with 
the  surface.  When  the  indirect  radiators  are  not  freely  sup- 
plied with  air,  or  the  velocity  is  low,  the  amount  of  heat  which 
is  discharged  is  small ;  when  the  velocity  of  the  air  is  high,  the 
amount  of  heat  taken  up  is  proportionally  greater.  According 
to  experiments  made  by  the  writer,  the  coefficient  of  heat 
transmission  increases  as  the  square  root  of  the  velocity  of  the 
air. 

The  amount  of  air  passing  over  a  given  surface  of  the  radi- 
ator can  be  estimated  quite  accurately  by  the  amount  of  heat 
given  off,  which  we  can  reasonably  suppose  in  this  case  to  be 


Test  by  Demon  &  Jacobus,  July,  1894. 


8o 


HEATING   AND    VENTILATING   BUILDINGS. 


all  utilized  in  warming  the  air.  At  a  temperature  of  about  60 
degrees,  I  heat-unit  will  warm  55  cubic  feet  of  air  I  degree 
(see  Table  VIII),  so  that  the  number  of  cubic  feet  of  air 
warmed  is  equal  to  55  times  the  total  number  of  heat-units 
given  off  from  I  square  foot  of  heating  surface  per  hour, 
divided  by  the  difference  of  temperature  of  entering  and  dis- 
charge air. 

NOTE. — Let  T  =  temperature  discharge  air,  t'  that  of  entering  air, 
H  =  total  number  of  heat-units  given  off  per  square  foot  of  surface,  a 
the  number  of  square  feet  of  surface.  Then, 

_   _     IT 

Cubic  feet  of  air  per  square  foot  heating  surface  =         _        . 

The  following  tests,  made  under  the  direction  of  the  writer, 
give  actual  results  obtained  in  testing  steam-pipes  in  a  current 
of  air  moving  at  different  velocities  : 

SUMMARY  OF  RESULTS.— TEST   OF  2"  STEAM-PIPE   WITH 
BLOWER. 


Heat  Transmis- 

Steam- 
pressure  by 
Gauge. 

Average 
Difference  of 
Temperature  of 
Steam  and  Air 
of  Room. 

Velocity  of  Air 
Passing  over 
Pipe,  Feet  per 
Second. 

sion  in  B.  T.  U. 
per  Square 
Foot  per  Hour 
for  each  Degree 
of  Temper- 

Increase in 
Temperature 
of  Air, 
Deg.  Fahr. 

Cubic  Feet 
of  Air  per 
Square  Foot 
per  Hour. 

ature. 

4-45 

123.72 

9.8 

6.32 

26.7 

148 

5-09 

I2O.3O 

9.4 

6.37 

28.4 

142 

5.38 

113.68 

4.1 

4.29 

42.O 

63 

5-86 

113-44 

4-5 

4.72 

42.4 

69 

5-27 

119.32 

6.7 

5.46 

34-9 

102 

5-15 

116.20 

5.5 

5.46 

37-4 

83 

5.20 

117.77 

12.48 

134.29 

7-i 

5-53 

35-9 

112 

13-70 

132.73 

6-7 

5.19 

37-3 

IOI 

12.10 

127.84 

6.0 

5-24 

40.9 

91 

12.25 

125.75 

5-5 

5.19 

43-1 

83 

13-73 

125-93 

4-3 

4-53 

48.3 

65 

13.55 

122.87 

4.4 

4.99 

5L4 

66 

12.97 

128.24 

25-35 

157.05 

8.6 

5.67 

37-1 

130 

27.10 

158.27 

9.1 

5-91 

37-7 

136 

27-54 

153.70 

6.7 

5.36 

44-8 

IOI 

28.21 

153.28 

6.3 

5.4i 

45-4 

100 

27.10   • 

146.68 

4-3 

4.20 

52.6 

65 

26.70 

147.19 

4.6 

4.61 

53-7 

70 

26.97 

152.69 

HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES.        8 1 


EXPERIMENTS   ON    INDIRECT   RADIATORS.* 


£ 

j 

|    Names  of  Radiators,  Engineers' 
and  Dates  of  Experiments. 

2s 

& 

P 

in 

Gauge  pressure, 

Strain. 

Tempera- 
tures. 

Diff. 
Temp. 

Oz.  Water  con- 
densed per  Foot 
per  Hour. 

3 
**  " 

Units  of 
Heat. 

1 

t/3 

S 

u 

W 

j| 

1 

a..- 

*e< 

3 

4 
5 

r 
7 
B 

y 

f  Gold's  pin  

60 
60 
70 
40 
60 

i 
i 

10 
10 

3 

5 
5 

2I5 

215 
2I5 
215 
239 
239 
222 
227 
227 

O 
O 
0 

o 

71 
42 

160 

156 

1&8 
170 
145 
142 
162 

160 
156 

147 
97 
98 
103 
109 
84 

215 
215 
215 
215 

168 
167 

1  80 
194 

139 

5  44 
5.09 
4.40 
4-88 
3-83 
3-84 
4.60 
5-00 
4.08 

III      340 
102      318 

106    275 
108    305 
128    239 
126,  240 
>45    288 
M9    313 
158    255 

i.58 
i.48 
1.28 
1.42 
1.42 

'•43 

1.  60 
1.61 
1.71 

C.  B.  Richards,  j  Novelty..  ..  
1873-4.         lG.  Whittier  
[Pipe  coil 

W.  J.  Baldwin,  J  Gold's  pin  

1885.           1  Compound  coil.  .  . 
W.  Warner,  1880,  Gold's  pin  
J    H    Mills  j  Walworth. 

1879.         j  Mills  

100  Cubic  Feet  of  Air  per  Foot  per  Hour,  Average. 

126 

231 
197 
214 
214 

212 

2I4 

214 

308 
3°7 

343 
3>9 
320 
3'9 
323 
354 
390 
379 

336 

1.50 

1.81 
i.  80 
2.66 

2-53 
1.94 
2.03 

2.13 

2.02 

2.15 
2.91 

3-68 
3-46 
2.48 

2.  51 
3.36 
3-52 
3-52 

2.96 

10 

4 

19 
20 

21 
22 
23 
24 

25 

Dr.  Gray,  1875.  Gold's  pin  
J.  R.  Reed,  1875,  whittier  
f  Gold's  pin.    
C.  B.  Richards,  J  Novelty     
1873-4.          1  G.  Whittier  
[Pipe  coil  

9o 
68 

20 

3 

i 
i 
i 

259 
222 
215 
215 

215 

33 
45 

0 

o 

0 

o 

125 
129 
139 
132 

102 

106 

c 

139 
132 

T02 

106 

226 
177 
215 
215 
215 

2»5 

6-54 
5-09 
9-15 
8.70 
6.66 
6.98 

400 

572 
544 
416 
436 

200  Cubic  Feet  of  Air  per  Foot  per  Hour,  Average. 

449 

344 
366 
495 

701 
744 
533 
540 

531 

510 

T    r>    T>     A    (Whittier... 

68 

68 
58 

60 

3 
3 
3 

i 
i 

i 

10 

5 
5 

222 
222 
222 
21.  S 
215 
215 
215 
239 
227 
227 

52 

52 
52 

o 

0 

o 

0 

81 
82 
82 

no 
114 
127 
129 

121 

87 
89 
159 

152 

75 
129 

121 

87 
80 
78 

68 
70 

170 
170 
170 
215 
215 
215 
215 

158 
145 
145 

5-50 
5.86 
7.92 
12.65 
ii  .90 
8-53 
8.64 
8-49 
8.16 
8.16 

J.  R   Reed  J  G  Whiuier  

18751         (Gold's  pin       
f  Gold's  pin  
C.  B.  Richards,  j  Novelty     
T873-4           I  G  Whittier 

1  Pipe  coil  . 
J.  H.  Mills,  1876.  Gold's  pin  
W  J   Baldwin  j  Gold's  pin 

Nov.,  1885.    '1  Compound  coil..  . 

300  Cubic  Feet  of  Air  per  Foot  per  Hour,  Average. 

536 

at 

11 

29 

30 

3' 

32 

J.  H   Mills   1876  Gold's  pin..     .. 

76^ 
60 
60 

10 

5 
5 

i 
i 
i 
i 

239 
227 
227 
215 
215 
215 
215 

90 
70 
70 

0 

o 

0 

o 

I58 
135 

1" 

3 

1 

% 

"3 
77 

76 

148 
158 

215 
215 
215 
215 

8.91 

8-93 
8.40 
15.92 
14.86 
10.14 

10.02 

433 

433 
420 
428 
428 
428 
428 

557 
558 
525 
995 
929 
634 
626 

3-76 

3-55 
3-34 
4-63 
4.32 
2-95 
2.91 

W.  J.  Baldwin,  j  Gold's  pin  
1885.            /Compound  coil., 
f  Gold's  pin  
C.  B.  Richards,  J  Novelty      
1873-4.          j  G.  Whittier  
[Pipe  coil  

400  Cubic  Feet  of  Air  per  Foot  per  Hour,  Average. 

428 

689 

3-64 

3  ? 

J   H   Mills,  j  Gold's  pin  . 

& 

6 
6 

230 
230 

88 
88 

158 
142 

70 

54 

142 
142 

10.04 

8.88 

467 

534 

628 

555 

592 

4.42 
3-9* 

1876        1  Walworth 

35 

3r 

500  Cubic  Feet  of  Air  per  Foot  per  Hour,  Average. 

4-17 

J   H.  Mills,  j  Walworth  

85 
76* 

20 

20 

259 
259 

90 

160 

166 

70 

76 

169 

169 

13.69 
15.16 

636 
649 

856 
948 

5.06 
5  61 

1876         \  Gold's  pin 

600  Cubic  Feet  of  Air  per  Foot  per  Hour,  Average. 

643 

902 

5-34 

•  i 

J.  H.  Mills,  j  Walworth  . 

7^ 

3 

3 

222 
222 

90 
90 

142 

145 

52 

55 

132 
132 

ii.  61 
12.54 

726 
734 

726 
784 

755 

5-5° 

5-94 

5-72 

1876.        |  Gold's  pin  

700  Cubic  Feet  of  Air  per  Foot  per  Hour.  Average. 

39 

40 

J.  H.  Mills,  I  Gold's  pin  

77 
85 

7* 

227 
233 

94 

79 

M5 

56 

133 
154 

15-30 

855 
888 

839 
956 

6.31 

6.21 

1876.        ")  Nason    .  . 

800  Cubic  Feet  of  Air  per  Foot  per  Hour,  Average. 

872 

898 

6.26 

*  From  John  H.  Mills'  work  on  Heat,  by  permission. 

82 


HEATING  AND    VENTILATING   BUILDINGS. 


Q 
Z 

S 

i 

EN 

£ 

</>" 
»J 
O 

< 
S 
Oi 

£     . 

£  % 

Q   ~ 

Z   -5 


H    CL 

<  D 


U 


Units  of  Heat 
per  Sq.  Ft. 

.s«a 

•  $%  S 

3      Qc/1  cd 

:   v^± 

Radiators  with  Water  Circulation.  . 

t'imf^tii 

IS 

t  T^  ^  °  ?  o  ~ 

00    t^ 

^S    Q"  m  <T!  <0 

rood  rooo  ro 

NOTE.—  For  Nos.  5,  15,  17,  and  19  the  heat  recorded  is  that  due  to  the  amount  of  steam  condensed  (see  1  able  XII). 

imilar  Conditions  and  Temperatures. 

[ 

ic-x 

s:-;S''8ls:s5;5:l,|? 

?ftiU!f8,*fr 

oo  o\ 

oooo 

CN     P) 

"o 

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—  '  j"J 

3 

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t-     M 

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U  *-*!V 

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4 

OO          Ov         10         t^ 

io       "5-       pi        10 

[^  w    ro  t^  i- 
vo    Pi  vo  O\  6 

PI               «M 

Difference  of 
Temperature. 

•3-d 
uiV 

p[03     pUB 

OOO    OOPioOioOPlw-* 
-^-  10  o  o>  t^oo  M   -  oo  r^  t-^ 

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jo  mesas 

SlffS'R'BSS^JSUI 

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t>.  10  N    O-  Pi  OO    -4-03 

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• 

Temperatures. 

Air  to  be 
Warmed. 

d 

1 

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, 

VO    f--vo    Pi  vo    O    t^  t~~ 
•*4-  ^t  rovo  vo    t^  io  10 

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in 

O    OOOOOOO    P)  VO    PI 
«        «   «S  l^VO    PI  vo 

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„'«« 

Water  or  Steam. 

Return. 

\o  io  N  N  \o  -^-co   «  o  io  in 

ro 

VO1       00          Ov         O 

00 

P)   O   •*  O  oo 
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1 

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JO  J33j£  S-IEnbg 

•^•00    O    10  "l-OO    O    O    10  O    O 

in        O    O  oo    O    O    O 
io        OVO    TJ-VO    OvO 

VC  O    t^.  CvOO 

-  -      -  M 

Radiators  boxed  in  Stacks,  open  below,  and  with 
Outlet  above  for  heated  Air,  the  duty  of  Radiator 
being  determined  by  the  Volume  and  Tempera- 
tures of  the  heated  Air. 

Engineers,  Radiators,  and  Dates. 

Averages  

fe  ":  S^;.74.  }  Bos  »"•  »«•  d~«I«-  i  -S: 

[^Sl^iMm.indirea  ]  ™S; 
^Uaia)  Compound  con  }  ££; 

^•.S-wtX-h01^^  iSSS: 

Averages  j  »««; 

•5fk  ^ 

11^1 

*•      ^       c' 

33     | 

W.  J.  Baldwin,  j  Box  coil,  nat.  draught,  water  
1886.  1  Compound  coil,  nat.  draught,  water 
J  H.  Mills,  j  Albany  cast,  nat.  draught,  water  
1835.  \  Box  coil,  nat.  draught,  water  
W.  J.  Baldwin,  \  Box  coil  
1886.  1  Compound  coil  
J.  H.  Mills,  j  Gold's  pin  
1885.  )  Mills'  indirect  
Staggered  Tube  Coil  Radiator,  Shakelton's,  water.. 
J.  H.  Mills,)  Mills'  indirect,  Shakelton's.  water  
188^.  1  Gold's  pin,  Shakelton's,  water  

JO}     'O£I 

M    p)    r*">  ^-  u-jvo    tvoO   O\  O    w 

«    fO^-^vo    t-00    0 

I!  O  H  N  ro  •* 

I  9  a  It  «  el 

HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES.        83 

From  the  general  results  shown  in  the  table  page  80  it  is 
seen  that  the  heat-units  given  off  per  square  foot  per  degree 
difference  of  temperature  equals  very  nearly  the  square  root  of 
four  times  the  velocity  in  feet  per  second.  That  is, 

h  =  V '4^. 

The  tables  pages  81  and  82  contain  an  extensive  summary 
of  tests  of  indirect  radiators,  abstracted  from  Mills'  work  on 
Heating  and  Ventilation,  and  are  of  especial  interest  as  show- 
ing the  close  agreement  in  results,  whether  water  or  steam  is 
used.  The  higher  results  in  this  table  agree  fairly  well  with 
the  rule  stated ;  those  for  natural  draught  are  much  smaller, 
and  approximately  equal  to  the  square  root  of  the  velocity  in 
feet  per  second. 

53.  Conclusions  from  Radiator  Tests. — The  general  re- 
;ults  of  radiator  tests  can  be  summed  up  as  follows  :  First,  that 
;he  values  for  heat  transmission  in  recent  tests  of  direct  radia- 
tors vary  greatly  and  differ  more  from  an  average  result  than 
from  those  given  by  Peclet,  and  consequently  his  results 
can  be  used  with  confidence  as  applying  to  modern  radiators. 
Second,  the  results  of  the  test  show  greater  differences  in  favor 
of  low  radiators  as  compared  with  high  ones  than  was  shown 
in  the  experiments  of  Peclet.  Third,  the  experiments  do  not 
show  any  sensible  difference  for  different  materials  used  in 
radiators  or  for  hot  water  or  steam,  provided  the  difference  in 
temperature  between  the  air  in  the  room  and  that  of  the  fluid 
in  the  radiator  is  the  same.  Fourth,  the  internal  volume  of 
radiators  is  of  value  only  in  lessening  the  friction  of  the  fluid. 
It  has  no  special  influence  on  the  results.  Fifth,  the  extended 
surface  radiators,  or  radiators  in  which  the  cast  iron  projects 
from  the  surface  into  the  air,  show  large  results  when  estimated 
on  the  basis  of  projected  or  plain  surface,  but  show  very  small 
results  when  estimated  on  the  basis  of  measured  surface. 
Sixth,  thin  radiators,  or  those  with  one  row  of  tubes,  always 
show  higher  efficiency  than  thick  ones  or  those  with  numerous 
rows  of  tubes.  Seventh,  comparative  tests  of  radiators  should 
only  be  made  between  radiators  of  similar  forms,  or  at  least 
those  which  have  about  the  same  amount  of  surface. 


HEATING  AND    VENTILATING   BUILDINGS. 


54.  Probable    Efficiency    of   Indirect    Radiators. — The 

velocity  with  which  the  air  will  move  over  radiators  when 
heated  a  given  amount  can  be  readily  computed  as  explained 
in  Article  33.  With  a  given  velocity  we  can  determine  from 
the  experiments  cited  the  probable  amount  of  heat  that  will  be 
given  off  per  degree  difference  of  temperature  per  hour  for 
natural  and  for  forced  circulation.  The  results  deduced  from 
experiments  are  given  in  the  following  tables : 

TABLE   FOR    NATURAL   CIRCULATION. 


Units  of  Heat  per 

Height  in  Feet. 

Temperature  of 
Entering  Air 
above  Room. 

Velocity  in  Feet 
per  Second. 

Degree  Difference 
of  Temperature, 
Average  per 
Square  Foot  per 

Corresponding 
Story  of 
Building. 

Hour. 

5 

50 

2.Q7 

1.72 

I 

10 

50 

4.17 

2.  02 

I 

17 

47 

5-3 

2.3 

2 

20 

45 

5-6 

2.36 

2 

25 

45 

6.3. 

2.52 

2 

30 

42 

6.6 

2.58 

3 

35 

42 

7-2 

2.68 

3 

40 

40 

7-5 

2.72 

4 

50 

40 

8.4 

2.  Si 

5 

TABLE  SHOWING  THE  HEAT-UNITS  PER  DEGREE  DIFFERENCE 
OF  TEMPERATURE  BETWEEN  THE  ENTERING  AIR  AND  THAT 
OF  THE  HEATING  SURFACE  FOR  DIFFERENT  VELOCITIES  OF 
AIR  APPLICABLE  IN  FORCED  CIRCULATION. 


.Velocity  in  Feet 
per  Second. 

Velocity  in  Feet 
per  Minute. 

Gauge-reading.  Inches 
of  Water-pressure. 

Heat-units  per  Degree 
Difference  of  Tem- 
perature per  Square 
Foot  per  Hour. 

I 

60 

0.002 

2 

2-5 

150 

0.014 

3.13 

5 

300 

0.064 

4-5 

7-5 

450- 

0.124 

5-5 

10 

600 

O.22 

6-33 

12.5 

750 

-      0.37 

7-i 

15 

QOO 

0.50 

7-75 

17-5 

IO5O 

0.65 

8-35 

20 

1200 

0.82 

9 

22.5 

1350 

1.  08 

9-5 

25 

1500 

1.28 

10 

55.  Temperature   produced   in   a   Room    by   a   given 
Amount  of  Surface  when  Outside  Temperature  is  High.— 


HEAT  GIVEN  OFF  FROM  RADIATING   SURFACES.         8$ 

Guarantees  are  often  made  respecting  heating  apparatus  that 
it  shall  be  sufficient  to  maintain  a  temperature  of  70  degrees 
when  the  external  air  is  at  some  fixed  point,  as  zero,  or  10 
below.  As  under  the  exact  conditions  of  the  guarantee  the 
trial  can  only  be  made  when  the  external  temperature  corre- 
sponds with  that  specified,  it  becomes  of  some  importance  to 
establish  an  equivalent  temperature  which  would  indicate  the 
efficiency  of  the  heating  apparatus  for  any  specified  condition. 
The  following  method  applicable  for  suchcomputations  and 
is  expressed  in  the  shape  of  a  formula  : 

Let  T  equal  temperature  of  radiator,  /'  that  of  room,  and  t 
that  of  outside  air  for  the  conditions  corresponding  to  the 
guarantee.  Let  B  equal  loss  from  room  for  i  degree  differ- 
ence of  temperature  ;  let  c  equal  the  heat-units  from  I  square 
foot  of  radiator  per  I  degree  difference  of  temperature  for  con- 
ditions corresponding  to  the  guarantee  ;  let  c'  denote  the  same 
values  for  other  conditions  ;  let  x  equal  resulting  temperature 
of  room,  /"  outside  air  for  the  actual  conditions,  R  equal  square 
feet  of  radiation. 

For  guaranteed  conditions, 

(/'  -;)B  =  c(T-t')R.      .....     (I) 

For  actual  conditions, 

(x-t")B  =  S(T-x)R.    .....     (2) 

Dividing  (i)  by  (2), 


When  /'  —  70,  T  =  220,  /  =  o,  and  c  =  1.8,  we  have 


The  coefficient  of  heat  transmission  c'  grows  less  as  the  tem- 
irature  in  the  room  becomes  higher,  as  already  shown  in  Art. 
46 ;  so  the  equations  can  only  be  solved  in  an  approximate 
manner.  The  following  table  gives  the  temperatures  in 
column  \,  which  a  room  would  have  for  various  tempera- 


86 


HEATING   AND    VENTILATING   BUILDINGS. 


tures  outside,  provided  there  was  sufficient  radiating  surface 
to  heat  the  room  to  70  degrees  in  zero  weather.  The  tempera- 
ture of  the  radiator  in  all  cases  is  assumed  to  be  that  due  to  3 
pounds  pressure  of  steam  by  gauge,  or  220  degrees. 

TABLE.* 


Temperature 
Outside  Air. 

Coefficient.t 
Heat  per  Square 
Foot  per  Hour 
per  Degree 

Total  Heat  per 
Square  Foot 
per  Hour. 

Resulting 
Temperature 
of  Room. 

Difference 
Temperature 
Radiator  and 
Room. 

—  1O 

I.S5 

288 

64.7 

155-3 

O 

.8 

270 

70 

150 

10 

•75 

253 

75-1 

144.9 

2O 

•  7 

236 

81 

J39 

30 

.65 

218 

86.5 

133-5 

40 

.6 

203 

93-i 

126.9 

50 

•  55 

1  88 

98.7 

129.3 

60 

•5 

172 

104.7 

II5-3 

70 

•45 

158 

110.5 

109.5 

80 

•  4 

142 

117.1 

102.9 

QO 

1-35 

130.5 

123-5 

96-5 

IOO 

i-3 

117 

130.3 

89.7 

Example  showing  Application  of  Table. — To  determine  by  a  test  of  the 
apparatus,  when  weather  is  60°,  whether  a  guarantee  to  heat  to  70°  in  zero 
weather  is  maintained,  operate  the  apparatus  as  though  in  regular  use  and  note 
the  average  temperature  of  the  room.  If  the  room  has  a  temperature  equal  to 
or  in  excess  of  104.7°  F.,  it  would  have  a  temperature  of  70°  in  zero  weather, 
all  other  conditions,  such  as  wind,  position  of  windows,  etc.,  being  the  same  as 
on  the  day  of  the  test. 

*  This  table,  although  calculated  for  steam  with  radiator  at  temperature  of 
220°  F.,  is  practically  correct  for  hot- water  radiation  or  for  steam  at  any  pressure 
and  temperature. 

f  Value  of  c'  in  formulae. 

\  Vol.  i,  Transactions  American  Society  Heating  and  Ventilating  En- 
gineers. 


CHAPTER   V. 

PIPE  AND   FITTINGS    USED   IN   STEAM   AND   HOT-WATER 

HEATING. 

56.  General  Remarks.— In  this   chapter  will  be  found  a 
concise  description  of  pipe  and  fittings  to  be  had  regularly  of 
most    dealers.     Such  a  description  is  entirely  unnecessary  to 
those  familiar  with  current  practice  in  the  industry  of  steam 
and  hot-water  heating;  but  as  the  writer  has  found  by  experi- 
ence detailed  knowledge  on  this  subject  is  often  required,  the 
following  descriptions  are  deemed  necessary. 

It  may  be  remarked  in  a  general  way,  that  for  conveying 
Cheated  air,  galvanized  or  tin  pipe  or  brick  flues  are  usually  pro- 
vided, but  for  the  purposes  of  conveying  steam  or  hot  water 
wrought-iron  pipe  is  used  almost  exclusively. 

57.  Cast-iron   Pipes   and   Fittings. — Cast-iron  pipe  was 
used  very  largely  at  one  time  for  both  supply-pipe  and  radiat- 
ing surface  in  hot-water  heating,  but  at  present  it  is  used  only 
to  a  limited  extent  in  greenhouse  heating.     For  this  purpose 
one  size  of  pipe  only  is  used,  and  this  is  4%"  outside  diameter. 
The  pipe  weighs  about  12  Ibs.  to  the  foot,  and  has  a  capacity  of 
£  gal.  per  foot.    The  pipes  are  usually  joined  by  socket-joints,  for 
which  purpose  a  socket  is  cast  on  one  end  of  each  pipe.     The 
joints  are  formed  by  inserting  one  end  of  one  pipe  into  the 


Fm.  32. — CAST-IRON  PIPE  WITH  SOCKET. 

socket  of  another  and  filling  the  interspace  either  with  melted 

*  lead,  iron-filings  and  sal-ammoniac,    sulphur,  or  cement,  and 

'  calking  thoroughly.     The  lead  joint,  which  is  ordinarily  used, 

is  formed  by  making  a  mould,  by  wrapping  a  hemp  rope  covered 

with  clay  around  the  joint,  with  a  pouring-place  on  top,  into 

which  the  melted  lead  is  run.     After  the  joint  cools  the  lead  is 

87 


88 


HEATING   AND    VENTILATING   BUILDINGS. 


driven  into  place  with  a  calking-iron.  The  rust-joint  is  a  very 
excellent  joint,  and  often  used.  It  is  made  with  a  cement 
formed  by  saturating  for  ten  or  twelve  hours  iron  turnings  or 
filings  with  sal-ammoniac.  This  cement  is  pressed  into  the 
socket,  and  then  pounded  tightly  into  place  with  a  calking-iron. 
Joints  made  with  Portland  cement  are  sometimes  used,  but  they 
are  likely  to  crack  from  the  heat,  and  cannot  be  recommended. 
The  regular  form  of  pipe  and  some  of  the  principal  fittings 
are  shown  in  Figs.  32  to  36. 


FIG.  33. — ELBOW  FOR  CAST-IRON 
PIPE. 


FIG.  34. — ROUND  TEE  FOR  CAST- 
IRON  PIPES. 


FIG.  35. — RADIATING  SURFACE  AND  PAN  FOR  HOLDING  WATER  TO  MOISTEN  Ail 

Two  or  more  lengths  of  pipe,  supported  on  special  brackets 
are  usually  run  in   parallel   lines  with  a  slight  descent  in  the 

direction   of   the    flow,   and    thus 
serve    both    for  radiating  surfaced 
and  circulating  pipes.    For  green-l 
house  heating,  where  the  air  is  to 
be  kept  moist,  a  special    pan  to 
be  filled  with  water,  as  shown  inl 
Fig-   35>  supported  by  the  pipes,, 
is  used  at  intervals. 

For  the  purpose  of  checking 
or  stopping  the  flow  a  stop  conl 
sisting  of  a  flat  plate,  which  can; 
be  set  at  any  angle  with  the  pipe,: 
and  of  a  form  as  in   Fig.  36,  is  used.     Each  length  of  cast-, 


FIG.  36.— VALVE  OR  STOP  FOR 
CAST-IRON  PIPE. 


PIPE  AND    FITTINGS.  89 

iron  pipe  is  sometimes  provided  with  flanges,  and  joints 
are  made  by  bolting  the  pipes  together,  packing  being  in- 
serted to  prevent  leaks.  These  are  inferior  to  the  calked 
joints. 

58.  Wrought-iron  and  Steel  Pipe.— Pipe  made  of  wrought 
iron  is  now  almost  exclusively  used  for  the  purposes  of  convey- 
ing steam  or  hot  water  in  heating  systems.  This  pipe  is  made 
in  a  number  of  factories  and  of  standard  sizes,  so  that  the 
pipe  obtained  from  one  is  reasonably  certain  to  fit  that 
from  another.  Wrought-iron  pipe  is  manufactured  from  iron 
of  the  proper  thickness,  which  is  rolled  into  pipe  shape,  and 
raised  to  a  welding  heat,  after  which  the  edges  are  welded 
by  drawing  through  a  die.  The  smaller  sizes,  ij  inch  and 
under,  are  butt-welded ;  the  larger  sizes  are  in  all  cases  lap- 
welded.* 

This  pipe  is  put  on  the  market  in  three  different  grades  of 
thickness :  first  the  standard  grade,  which  is  used  principally 
for  heating  purposes  ;  this  is  tested  to  a  pressure  of  250  Ibs. 
per  sq.  in.  and  has  the  dimensions  given  in  Table  XV ;  it 
'•is  manufactured  in  sizes  from  -J  in.  to  15  in.  in  diameter. 
Thicker  pipe,  called  extra  strong,  and  still  heavier  pipe-called 
double-extra  strong,  is  manufactured,  and  can  be  obtained  if 
required.  The  thick  piping  has  the  same  distinguishing  name 
as  pipe  of  standard  weight,  having  the  same  external  diameter, 
which  is  in  all  cases  that  of  the  internal  diameter  of  the  stand 
ard  pipe.  The  extra-strong  and  double-extra  strong  have 
smaller  diameters  than  would  be  implied  by  the  name ;  thus, 
for  instance,  inch  pipe,  standard  size,  has  an  inside  diameter  of 

*  The  process  of  lap-welding  is  as  follows  :  The  sheet  of  iron  is  rolled  to 
the  desired  thickness,  width,  and  length.  The  edges  are  then  scarfed.  It  is 
then  drawn  while  red-hot  by  means  of  an  endless  chain  through  a  bell-shaped 
die,  which  rounds  it  up  and  laps  one  edge  over  the  other.  The  whole  length 
is  put  into  the  furnace  and  heated  to  a  welding  heat,  and  afterward  pushed  out 
of  the  furnace  at  the  opposite  end  into  grooved  rolls  of  a  size  corresponding  to 
the  size  of  the  pipe.  The  inside  lap  is  supported  by  a  ball  attached  to  a  large 
bar  of  iron.  The  ball,  the  iron,  and  the  groove  in  the  roll  all  correspond  so 
that  the  roll  shall  produce  a  sufficient  pressure  upon  the  iron  and  the  ball  to 
force  the  laps  of  the  iron  firmly  together,  thus  producing  the  weld. — From  paper 
by  R.  T.  Crane,  Early  History  Wrought-iron  Pipe,  Fifth  Annual  Convention 
Master  Steam-Fitters'  Association. 


QO  HEATING   AND    VENTILATING   BUILDINGS. 

about  one  inch,  an  outside  diameter  of  1.315  inches,  while  the 
extra-strong  pipe  of  the  same  nominal  size  has  the  same  out- 
side diameter  and  an  inside  diameter  approximately  0.951  inch, 
while  the  double-extra  strong  has  the  same  outside  diameter 
and  an  inside  diameter  of  0.587  inch. 


FIG.  37.  —  SECTION  OF  STANDARD  PIPES  \  TO  3  INCHES  INTERNAL  DIAMETER. 


The  following'  table   eives  the  diameters,  external  and  in- 

o  o 

ternal,  and  weights  per  foot,  of  the  various  kinds  of  pipe.     In 


PIPE  AND   FITTINGS. 


the  table  *  the  normal  inside  diameter  is  the  actual  diameter,  or 
nearly  so,  for  the  standard  pipe;  sizes  to  ij  inch  are  butt- 
welded,  larger  sizes  lap-welded : 


Nom- 
inal Di- 
ameter 
(Name  ', 
Inches, 
f 

Actual 
Out- 
side 
Diam- 
eter, 
Inches. 

Actual  Inside 
Diam.,  In.t 

Thickness  of  Iron, 
Inches.  + 

Weight  per  Foot, 
Pounds  t 

Threads  per 
Inch. 

Extra 
Strong. 

Double'    Stan- 
Extra      dard 
Strong. 

Extra 
Strong. 

Double 
Extra 
Strong. 

Stand- 
ard. 

Extra 
Strong. 

Double 

Extra 
Strong 

M 

i 

% 

% 

2 

i    »W 

'    H 
4« 

i 

0.405 
0.54 
0.675 
0.84 
0.105 

::li5 

1.9 

2-375 

2.875 

3-5 
4 
4-5 

5-563 
6.625 

.205 
•  294 
.421 
•  542 
•736 
•  951 
.272 
-494 
•933 
-315 
.892 
3-358 
3-8i8 



0.068 
o  088 

O.IOO 



0.24 

0.29 

27 
18 
18 
14 
M 
"'i 
1114 

nJ4 
8 
8 
8 
8 
8 
8 
8 

0.56 
0.84 

1.12 
1.67 
2    24 

2.68 
3-6i 
5-74 
7-54 
9.00 
10.66 
12  49 

o  74 
1.09 

i-39 
2.17 
3.00 
3-63 
5.02 
7.67 
10.25 
'2-47 
14.97 

1.70 
2-44 
3-65 
5.20 
6.40 
9.02 
13.68 
18.56 
22.75 
27.48 

"38-12 
53-" 

0.244 
0.422 
0.587 
0.885 
i.  088 
1.491 
1-755 
2.284 
2.716 
3-136 

o.  109 

0.113 
0.134 
0.140 

0.145 
0.154 
0.204 
0.217 

0.226 

0.237 

0.149 

0-157 
0.182 
0.194 
0.703 

O.22I 
0.280 
0.304 
O.32I 
0.341 

0.298 
0.314 
0.364 
0.388 
0.406 
0.442 
0.560 
0.608 
0.642 
0.682 

4-813 
5-75 

4.063 
4.875 

0.259 

0.280 

0-375 
o  437 

0-75 
0.875 

14.50 
18  76 

20.54 
28.58 

Steel  Pipe. —  For  nearly  every  purpose  of  manufacture, 
soft  steel  has  replaced  wrought  iron,  and  this  will  doubtless 
be  the  case  some  time  so  far  as  piping  is  concerned.  Up  to 
the  present  time,  however,  the  pipe  made  of  steel  has  not  been 
as  soft  as  that  of  wrought  iron,  and  is  more  likely  to  dull  and 
injure  the  dies  and  cutters  used  by  workmen.  It  is  often  not 
so  well  welded,  and  is  more  likely  to  split.J  Solid-drawn  pipe 
has  been  made  to  a  limited  extent,  and  is  very  likely  at  no 
distant  date  to  supersede  welded  pipe  of  all  descriptions. 

Each  length  of  pipe  as  sold  is  provided  with  a  collar  or 
coupling  screwed  on  to  one  end  and  has  a  thread  cut  on  the 
other  end.  Connections  are  made  by  screwing  the  threaded 
end  of  one  pipe  into  the  coupling  on  the  other.  There  is  no 
standard  length  of  pipes,  the  range  usually  being  from  16  to 
24  feet,  with  occasional  short  pieces.  It  can  be  ordered  in 
lengths,  cut  as  desired  for  slightly  extra  prices  ;  but  it  can  be 
readily  cut  any  length,  and  right-  or  left-handed  threads  may 
be  cut  as  desired.  It  is  quite  malleable,  and  when  heated  may 

*  See  more  extended  table  in  Appendix. 

f  Approximate,  outside  diameter  only  is  exact. 

\  1898.     Steel  pipe  can  be  purchased  equal  in  every  respect  to  wrought  iron. 


^2  HEATING   AND    VENTILATING   BUILDINGS. 

be  bent  into  almost  any  shape  by  a  skilful  workman  without 
materially  changing  the  form  of  its  cross-section. 

59.  Pipe  Fittings. — Fittings  for  connecting  pipes  and  for 
giving  them  any  required  direction  with  respect  to  each  other 
are  regularly  on  the  market.  These  fittings  are  mostly  made 
of  cast  and  malleable  iron,  the  prominent  exception  being 
straight  couplings  with  right-handed  threads  in  both  ends, 
which  are  usually  of  wrought  iron. 

Cast-iron  fittings  are  generally  preferred  to  those  of  malle- 
able iron  in  any  system  of  piping  for  heating,  for  the  reason 
that,  being  harder  than  the  pipe  and  less  elastic,  they  are  not 
likely  to  stretch  and  yield  sufficiently  to  permit  leakage  when 
the  pipes  are  connected  ;  if  broken,  a  fracture  can  readily  be 
detected  and  a  new  fitting  supplied.     Malleable-iron  fittings 
frequently  stretch  if  pipes  are  screwed  somewhat  too  hard,  so 
that  future  expansion  and  contraction  is  quite  certain  to  cause 
a  leak.     If  it  is  necessary  to  take  down  a  long  line  of  pipe] 
in  which  no  removable  joints  occur,  a  cast-iron  fitting  can  be 
easily  broken,  thus  often  saving  more  time  than  the  cost  of  the* 
fitting,  while  the  malleable  fitting  cannot  be  so  disposed  of. 
It  is  quite  true  that  malleable  fittings  are  stronger  than  cast- 
iron  when  of  equal  weight,  but  those  on  the  market  are  much] 
lighter  than  the  cast-iron    ones;  and,  moreover,  the  standard] 
fittings  are  abundantly  strong  for  any  pressures  likely  to  be 
sustained  in  ordinary  systems  of  heating. 

The   standard    pipes   are    considerably    stronger  than  the 
standard  fittings,  and  if  extra  heavy  pressures  are  required,  sayj 
looto  150  pounds  per  square  inch,  it  is  advisable  to  use  special] 
fittings,  which   differ    from   the    ordinary   ones    principally   in 
weight. 

The  fittings  which  are  on  the  market  can  be  divided  into 
various  classes,  depending  upon  their  use. 

Pipe  Connections. — For  joining  pipes  in  the  same  line  there] 
is  provided,  first,  the  wrought-iron  coupling  shown  in  Figs.  38; 
to  40. 

The  coupling,  usually  with  plain   exterior,  has  right-hand 
threads  cut  in  both  ends,  and  is  used  principally  in  erecting  a 
pipe  line  where  the  construction  is  continuous  from  one  end  toj 
the  other.     A  reducing  coupling,  Fig.  40,  is  frequently  usedj 


PIPE  AND   FITTINGS.  93 

for  uniting  pipes  of  different  sizes.  In  cases  where  it  is 
necessary  to  "  make  up  "  or  unite  lines  of  piping  which  come 
together  from  different  directions,  a  left-hand  thread  can  be 
cut  on  the  end  of  one  of  the  pipes  and  the  junction  formed  by 


FIG.  38.  FIG.  39.  FIG.  40. 

COUPLING.  RIGHT-AND-LEFT  COUPLING.       REDUCING  COUPLING. 

using  a  coupling  similar  to  the  above,  but  with  a  right-hand 
thread  cut  in  one  end  and  a  left-hand  thread  cut  in  the  other, 
such  a  coupling  being  known  as  a  right-and-left  coupling.  To 
use  this  coupling  room  is  required  for  end  motion  of  one  of 
the  pipes  sufficient  to  insert  it. 

In  making  up  right-and-left  couplings  care  must  be  taken 
that  both  threads  on  the  pipe  engage  with  those  in  the  coup- 
ling at  about  the  same  instant.  This  can  be  done  by  screwing 
the  coupling  by  hand  on  the  end  of  each  pipe,  and  counting 
the  number  of  turns  that  can  be  made,  noting  the  number  of 
threads  in  sight  after  the  joint  is  made  up.  This  coupling, 
while  sometimes  difficult  to  use,  forms  the  most  certain  method 
of  uniting  two  pipe  lines  so  that  they  will  not  leak.  For  join- 
ing pipes  a  coupling  which  separates  into  three  pieces,  termed 
a  union,  is  often  employed.  The  parts  of  the  union  are 


FIG.  41. — THE  UNION.  FIG.  42. — SECTION  OF  UNION. 

screwed  onto  the  ends  of  the  pipe,  and  are  drawn  together  by 
a  revolving  collar  which  engages  with  the  thread  on  one  of  the 
pieces.  The  joint  is  formed  either  by  drawing  flat  faces  in  the 
union  against  some  elastic  and  soft  material,  as  packing,  or 
else  by  producing  contact  of  ground  and  fitted  metallic  sur- 
faces. Pipes  are  also  held  together  by  screwing  flanges  to  the 
pipes,  and  drawing  these  flanges  either  in  contact  or  against  a 


94  HEATING   AND    VENTILATING   BUILDINGS. 

ring  of  packing  by  bolts  (Fig.  43).     Such  a  joint  is  called  a 
union 


FIG.  43. 
FLANGE  UNION. 


FIG.  44. 
LONG-THREADED  NIPPLE  AND  LOCK-NUT. 


Lengths  of  pipe  are  frequently  made  up  by  a  short  piece 

•  of  pipe  with  a  long  screw-thread  cut  on  one  end,  onto  which  is 
screwed  a  very  short  collar  or  lock-nut,  Fig.  44.     The  junction^ 
is  made  between  two  ordinary  pipe  couplings  by  first  screwing' 
the  long  thread  into  one  pipe  coupling  until  the  piece  is  short 

•  enough  to  be  slipped  into  position,  then  it  is  screwed  into  the 

•  other  coupling  by  unscrewing  from  the  first.     When  screwed 
'home,  the  collar  or  lock-nut  is  turned  tightly  against  the  first 
coupling,  forming  a  steam-tight  joint  either  by  metallic  contact 
or  by  use  of  packing. 

Pipe  Bends   and  Elbows. — For  changing    the   direction   of] 
pipe  lines  there  can  be  purchased  elbows  with  bends  of  45  or; 
90  degrees,  also  reducing  elbows  in  which  one  opening  is  for 
smaller  size   of  pipe  than  that  of  the  other.     The  QO-degree 
elbow  can  be  had  either  with  right  threads  in  both  ends  or 
with  right  and   left  threads,  as  required.     The  right-and-left 
threaded   elbow   can   be   used   for   making  up  two  pipe   lines 
in  a  manner   similar    to    that   described    for   a   right-and-left 

•  coupling. 


FIG.  45 
'90°  CAST-IRON  ELBOW. 


FIG.  46. 
45°  CAST-IRON  ELBOW. 


FIG.  47. 
90°  REDUCING  ELBOW. 


The  internal  diameter  of  elbows  is  somewhat  in  excess  oi 
that  of  the  external  diameter  of  the  pipe,  and  the  radius  of  the 
.bend  is,  according  to  Briggs'  table  (Van  Nostrand  Science 


PIPE  AND    FITTINGS. 


95 


Series,  No.  68),  equal  in  nearly  every  case  to  the  diameter  of 
the  pipe  plus  a  constant  which  varies  from  f  inch  for  the 
smallest  size  of  pipes  to  \  inch  for  the  largest  size.  For  the 
sizes  of  pipes  used  in  heating  the  radius  of  curvature  is 
practically  equal  to  that  of  the  diameter  of  the  pipe  plus 
£  inch. 

Where  the  friction  caused  by  a  standard  elbow  is  detri- 
mental, special  fittings  (Figs.    48    and   49)    can    be    obtained 


FIG.  48. — LONG-RADIUS  ELBOW.     FIG.  JQ. — QUARTER  BEND  OF  PIPE. 

in  which  the  radius  of  curvature  is  from  two  to  three  times 
that  given.  Such  fittings  are  especially  desirable  in  heating 
by  hot-water  circulation,  and  often  permit  the  use  of  smaller 
pipes  than  would  be  possible  with  standard  fittings. 

Pipe  Junctions,  Tees,  Y's,  etc. — For  the  purpose   of  taking 
off   one   pipe  line   from   another  special   fittings   can   be  had, 


FIG.  50. 

PLAIN  TEE— OPENINGS  ALL  SAME 
SIZE,  THREADS  RIGHT-HANDED. 


FIG.  51. 

REDUCING  TEE — OPENINGS  VARIOUS 
SIZES.     (In  describing  state  diam- 
eter of  branch  last.) 


FIG.  52. 
LONG-RADIUS  TEE. 


FIG.  53. 
Y  FITTING. 


FIG.  54. 
LONG-RADIUS  Y. 


90  HEATING  AND    VENTILATING  BUILDINGS. 

which  are  designated,  according  to  their  shape,  as  tee,  cross, 
side-outlet  elbow,  and  Y-branch,  all  of  which  can  be  bought 
with  the  openings  for  the  same  or  different  sized  pipes  in  any 
combination  required. 

These  various  fittings  are  shown  in  the  annexed  engrav- 
ings. 


FIG.  55. ' 
SIDE-OPENING  ELBOW. 


FIG.  56. 
CROSS. 


FIG.  57. 
REDUCING  CROSS 


Miscellaneous  Fittings. — For  reducing  the  size  of  opening 
in  a  fitting,  bushings  of  cast  (Fig.  58)  or  malleable  iron  can  be| 
used;  for  closing  up  the  end  of  fittings  a  screwed  plug  (Fig.  59) 
can  be  employed ;  and  for  closing  the  end  of  a  pipe  a  screwed 
cap  (Fig.  60)  can  be  used.  Where  a  coil  of  pipe  is  desirable,  it 
can  be  formed  by  screwing  pipes  into  U-shaped  fittings,  called 
return  bends.  These  can  be  had  with  either  right  threads  or 
right-and-left  threads,  and  inclose  (Fig.  61)  or  open  pattern 
(Fig.  62),  and  with  the  threads  tapped  so  as  to  give  nearly  any 
pitch  or  rake  of  the  pipe.  For  slightly  changing  the  position 
of  a  pipe  an  offset  (Fig.  63)  can  be  used.  To  prevent  leaking 
where  a  long-threaded  nipple  has  been  used,  a  lock-nut  can  be 
screwed  on  against  a  grummet,  or  ring  of  packing. 


FIG.  58. — BUSHING.        FIG.  59. — PLUG. 


FIG.  60.— CAP. 


FIG.  6r.  FIG.  62. 

RETURN  BENDS. 


FIG.  63. 
OFFSET. 


FIG.  64. 
LOCK-NUT 


PIPE  AND   FITTINGS. 


97 


Fittings  can  also  be  had  for  erecting  parallel  lines  of  pipe, 
as  shown  in  Figs.  65  and  66;  they  are  termed  branch  tees,  and 


FIG.  65.— BRANCH  TEE,  PLAIN. 


FIG.  66. — BRANCH  TEE,  WITH  BACK  OUTLET. 

can  be  had  for  almost  any  number  of  pipes,  and  for  sizes 
varying  from  three-quarter  to  three  inches.  The  distance  be- 
tween centres  cf  branches  is  varied  somewhat,  but  is  usually 

2  inches  for  three-quarter-inch  pipe,  2^  inches  for  one-inch  pipe, 

3  inches  for  one-and-a-quarter-inch  pipe,  and  3^  inches  for  one- 
and-a-half-inch  pipe.     The  branch  tees  are  fitted  with  opening 
for  supply-pipe  and  discharge-pipe  either  in  end  or  side  as 
specified.     In  those  made  for  circulation  the  holes  are  tapped 
with  right-hand  threads  ;  those  made  for  box-coils  are  tapped 
for  left-hand  thread  on  branches. 

Short  pieces  of  pipe  called  nipples  can  be  had  of  any  length 

required,  provided  with  right-hand  threads 

cut  on  both  ends,  or  with  right  thread  on 

one    end    and    left    thread    on    the    other. 
'  Short  pieces  of  pipe  called  quarter  or  eight- 
)  bends   (Fig.  49)  may  be   used    in   place  of    SHOULDER 
*  elbows  when  a  long-radius  turn  is  required.      NIPPLE. 

In  addition  to  the  fittings  mentioned  there  can  be  had,  for 

supporting  the  pipes  to  side  walls,  hooks  and  hook-plates  with 
(  curved  or  straight  arms,  ringed  plate,  and  coil-stand,  as  desired. 


FIG.  67. 


FIG.  68. 
CLOSE 
NIPPLE. 


FIG.  69. — HOOK-PLATE. 


98 


HEATING   AND    VENTILATING   BUILDINGS. 


There  can  also  be  had  hangers  of  various  patterns  for  sup- 
porting and  holding  pipes  from  ceilings.      These  are  of  great 
variety  of  pattern,  and  are  made  so  that,  if  desired,  they  can  b 
put  on  after  the  piping  is  in  place. 

The  principal  standard  fittings  as  above  described  are  als 
made  of  brass. 


FIG.  70. — EXPANSION-PLATE. 


FIG.  71. — RING-PLATE. 


FIG.  72. — COIL-STANDS. 

Ceiling  and  Floor  Plates  are  collars  used  to  hold  the  pipe 
in  place,  and  to  prevent  overheating  of  woodwork  by  the  stearr 
or  hot  water.  These  are  often  made  in  halves,  which  may  b 
slipped  on  over  the  pipes,  and  are  fastened  to  the  woodwor 
by  screws,  thus  holding  the  pipe  in  position  and  keeping  it  frorr 
contact  with  wood. 

60.  Valves  and  Cocks. — The  fittings  used  for  the  purpos 
of  stopping  the  passages  in  pipes  are  operated  by  movin, 
a  disk  across  the  pipe  with  or  without  rotation,  or  by  simpb 
turning  through  an  angle.  The  first  class  have  been  general^ 
called  valves,  the  second  cocks. 

Valves  are  of  two  classes:  the  globe  valve  (Fig.  73),  whic 
closes  an   opening  in  a  diaphragm  parallel  to  the  direction  o 
flow,  and  the  gate  valve  (Fig.  74),  which  closes  an  opening  a 
right  angles  to  the  pipe. 

The  globe  valve  forms  a  serious  obstruction,  since  any  flui< 
in  passing  through  it  must  make  two  turns,  each  nearly 


PIPE  AND   FITTINGS. 


99 


right  angle;  while  the  gate  valve  when  open  presents  little  or 
no  resistance. 


FIG.  73. — GLOBE  VALVE. 


FIG.  74. — GATE  VALVE. 


The  globe  valve  is  much  more  simple  in  construction  than 
the  gate  valve,  is  cheaper,  and  often  will  answer  all  require- 
ments for  steam-heating,  but  will  seldom  do  for  hot-water  heat- 
ing. It  should  be  set  so  that  the  valve  closes  against  the  flow ; 
when  set  in  the  opposite  way  accidents  might  happen — for  in- 
stance, if  the  valve  should  be  detached  from  the  stem  it  could 
not  be  opened,  although  the  stem  would  move  apparently  all 
right.  It  will  be  noted  that  the  diaphragm  of  the  globe  valve 
forms  an  obstruction  in  the  pipe,  which  extends  to  the  centre, 
and  if  the  stem  of  this  valve  be  set  vertical  when  used  for  a 
horizontal  pipe  it  is  likely  to  cause  the  pipe  to  stand  half  full 
of  water.  Whenever  used  in  steam-heating,  on  a  horizontal 
pipe,  the  stem  should  be  placed  in  a  horizontal  position,  so  that 
it  will  not  interfere  with  the  drainage  of  water  of  condensation 
from  the  pipe. 

The  construction  of  the  gate  valve  varies  in  detail  as  made 
by  different  manufacturers,  but  it  in  general  consists  of  a  gate 
which  is  moved  across  the  opening  in  the  pipe  by  turning  the 
stem.  When  the  gate  reaches  the  bottom  of  the  pipe  it  moves 
laterally  sufficient  to  bring  a  strong  pressure  on  the  seat. 


100        HEATING   AND    VENTILATING   BUILDINGS. 


These  valves  are  made  with  a  stem  which  rises  with  the  gate 
as  shown  in  Fig.  '74,  or  with  one  which  remains  in  one  position, 
the  gate  travelling  up  the  stem.  This  latter  form  is  objection- 
able, as  one  cannot  tell  by  looking,  whether  the  valve  is  open 
or  closed. 

Globe  valves  are  made  with  a  solid  metallic  seat,  as  in  Fig. 
73 ;  or  with  a  seat  made  of  soft  metal  or  packing,  as  in  Fig.  75, 
of  such  a  form  that  it  can  be  replaced  whenever  the  valve 
begins  to  leak. 


FIG.  75. — GLOBE  VALVE  WITH  DISK  SEAT.       FIG.  76. — ANGLE  VALVE. 

Angle  Valves  (Fig.  76)  are  made  in  the  same  general  way 
as  globe  valves,  except  that  the  openings  are  at  right  angli  s  to 
each  other.  They  cause  a  slightly  greater  resistance  to  mc-tion 
than  the  ordinary  elbow,  but  not  sufficient  to  prevent  their  use 
for  any  system  of  heating.  The  seats  are  either  metallic  or  of 
soft  material,  which  can  be  removed. 

Stuffing-boxes. — In  all  classes  of  valves  a  cavity  is  left  around 
the  stem,  which  must  be  filled  with  some  packing  material  by 
turning  back  a  cap-screw.  Hemp,  lamp-wicking,  asbestos  fibre, 
well  oiled  and,  if  possible,  covered  with  plumbago,  will  make 
satisfactory  packing  for  this  purpose.  Patent  ring  packing 
can  be  purchased,  usually  made  of  asbestos  fibre  soaked  in  oil, 
and  serves  an  excellent  purpose. 


PIPE  AND   FITTINGS. 


IOI 


Radiator  Valves. — These  are  forms  of  angle  valves  with 
fittings  making  them  especially  convenient  for  radiator  connec- 
tions, being  plain  as  shown  in  Fig.  77  or  with  an  attached 
union  as  in  Fig.  78.  These  are  often  nickel-plated. 

Radiator  valves  can  be  had  with  pedal  attachment,  so  that 
they  can  be  opened  or  closed  with  the  foot. 

The  various  kinds  of  valves  which  have  been  described  are 
made  with  sockets  for  screwed  connections  to  the  pipes,  or 
with  flanges  which  are  to  be  bolted  to  similar  flanges  screwed 
on  the  pipes  as  desired.  They  can  also  be  had,  especially  for 
the  larger  sizes,  with  either  brass  or  iron  bodies. 


FIG.  77.— RADIATOR  VALVE.  FIG.  78.— HOT-WATER  VALVE. 

Cross  Valves. — A  form  of  angle  valve  with  one  supply  and 
ind  two  opposite  discharge  openings  is  sometimes  convenient, 
md  is  termed  a  cross  valve.  (See  Fig.  83.) 

Corner    Valves,    in   which   the  openings   are  at   the    same 
>vel  but  at  right  angles,  can  be  purchased  if  desired. 

Cocks. — A  plug,  slightly  conical,  provided  with  one  or  more 
>rts  or  holes  through  it,  and  arranged  so  that  it  can  be  turned 
any  direction,  is  termed  a  cock.  When  there  is  but  a  single 
role  it  is  called  a  plain  cock.  When  two  or  more  holes  at 
ingles  to  each  other,  it  is  called  a  two-way  or  three-way  cock, 
dnce  water  can  be  directed  in  two  or  more  directions  by  vary- 
ing the  angle  through  which  the  plug  is  turned.  Cocks  are 
rery  little  used  in  steam-heating ;  as  ordinarily  made  they  are 
)t  to  leak,  and,  besides,  do  not  provide  a  full  opening  for  the 
luid. 


IO2  HEATING   AND    VENTILATING   BUILDINGS. 

Improved  cocks  with  larger  openings  and  with  packed  ends 
are  now  much  used  on  the  blow-off  pipes 
from  boilers,  and  are  for  this  purpose  su- 
perior to  valves. 

Quick-opening  valves  (Fig.  79)  for  use 
on  hot-water  pipes  are  often  made  on  the 
same  plan  as  cocks,  and  do  excellent  ser- 
vice in  these  places. 

Check  Valves. — Where  it  is  necessary 
that  the  flow  should  always  take  place  in 
the  same  direction  and  there  is  danger  of 
a  reverse  flow,  check  valves  are  employed. 
These  are  usually  of  a  similar  pattern  to 
the  globe  valve,  the  seat  being  at  right 
angles  to  the  direction  of  flow,  with 
either  a  flat  or  ball  valve  (Figs.  80,  81). 

FIG.  79.— QUICK-OPENING  In  this  class  the    valve    is    held    in  place 
RADIATOR  VALVE  FOR 
HOT-WATER.  by  its  own  weight    or    by  the  weight  of 

the  fluid  in  case  of  reverse  flow.  They  are  made  for  hori- 
zontal pipes,  vertical  pipes,  or  angles.  One  known  as  the 
swinging-check  valve,  in  which  the  seat  is  at  an  angle  of  about 
45  degrees  to  the  direction  of  flow  (Fig.  82),  offers  less  resist- 
ance to  the  fluid,  and  is  generally  to  be  preferred. 

6l.  Air- valves. — It  is  necessary  to  provide  means  for  allow- 
ing the  air  to  escape  in  systems  of  steam  and  hot-water  heating. 
Air  is  heavier  than  steam,  and  although  it  will  mix  with  it  to 
a  great  extent,  it  will  finally  settle  at  or  near  the  bottom 
of  a  radiator  or  pipe  filled  with  steam.  Air  is,  however, 
much  lighter  than  water,  and  it  will  gather  in  any  bends 
that  are  convex  upward  and  in  the  upper  part  of  radiators 
filled  with  water,  and  unless  removed  it  will  prevent  the  circu- 
lation. 

For  removal  of  the  air  several  forms  of  valves  and  cocks 
have  been  especially  manufactured.  These  are  usually  made 
of  J-  or  ^-inch  pipe  size,  and  vary  in  quality  and  design  from 
the  simplest  valve  to  be  opened  by  hand  to  a  complicated  auto- 
matic pattern,  which  permits  the  escape  of  air,  but  not  of  water 
or  steam. 

One  of  the  simplest  patterns  of  air-valves  is  shown  in  Fig. 


PIPE  AND   FITTINGS. 


103 


FIG.  So. — HORIZONTAL      FIG.  ST. — HORIZONTAL 
CHECK  WITH  BALL  CHECK  VALVE. 

CLACK. 


FIG.  82. — SWINGING 
CHECK. 


Globe  Valve. 


Angle  Valve. 


Cross  Valve. 


Horizontal  Check  Valve.  Angle  Check  Valve.      Vertical  Check.  Steam  Cock, 

Flanged  Ends. 


Expansion  or  Slip  Joint.  Steam  Cock,  Screwed  Ends. 

FIG.  83. — PRINCIPAL  VALVES  AND  STOPS  USED  IN  HEATING. 


104 


HEATING   AND    VENTILATING   BUILDINGS. 


84.     This  can  be  had  with  a  bibb  if  desired,  also  with  various 
forms  of  handles  or  keys,  and  with  nickel  or  brass  finish. 

Automatic  air-valves  are  made  of  a  great  variety  of  pat- 
terns. Those  for  steam-radiators  are  all  closed  by  the  expan- 
sion of  some  material  Fig.  85  shows  an  expansion  air-valve, 
in  which  the  valve  is  closed  by  the  expansion  of  a  curved 
metallic  strip.  The  valve  will  remain  open  until  this  curved 


FIG.  84. — SIMPLEST  PATTERN 
AIR-VALVE. 


FIG.  86. 
AUTOMATIC  AIR- VALVE. 


FIG.  87. — COMPOSITION  AUTO- 
MATIC VALVE. 


FIG.  85.  —  BRECKEN- 

RIDGE  AUTOMATIC 

AIR-VALVE. 


strip  becomes  nearly  equal  in  its  temperature  to  that  of  the 
steam ;  the  heat  then  increases  its  length  and  it  bends  out 
sufficiently  to  close  the  valve.  A  drip-pipe  is  provided  for  re- 
moving any  water  of  condensation  escaping  from  the  air-valve. 
Another  form,  which  has  in  the  past  .been  extensively  used, 
is  shown  in  Fig.  86.  In  this  case  the  interior  tube  A  is  heated 
more  than  the  frame  bb  ;  this  serves  to  press  the  valve  c  against 
the  end  of  the  tube  when  it  is  heated,  thus  closing  the  orifice. 
This  is  best  adapted  for  use  in  a  vertical  position. 


PIPE  AND   FITTINGC. 


105 


A  form  of  air-valve  now  in  extensive  use  is  shown  in  Fig. 
87.  In  this  a  composite  material  which  expands  rapidly  when 
heated  is  used  instead  of  metal.  It  is  claimed  for  some  of 
these  valves  that  with  suitable  adjustment  of  the  top  screw  the 
temperature  of  the  radiator  will  be  automatically  maintained 
at  any  desired  point — a  mixture  in  any  required  proportion  of 
air  and  steam  being  maintained  in  the  radiator  by  this  action. 

To  prevent  escape  of  water  and  injury  to  furniture  a  radia- 
tor-valve with  a  float  attachment  is  often  used,  as  shown  in 
iFig.  88.  The  valve  is  closed  when  heated,  as  in  Fig.  87,  by 
the  expansion  of  a  composite  substance  ;  it  is  connected  to  a 
ifloat,  so  that  if  water  passes  into  the  air-valve  the  float  will 
rise  and  close  the  orifice  regardless  of  the  temperature. 


FIG.  88.— RADIATOR  AIR-VALVE 
WITH  FLOAT. 


FIG.  89. — HOT-WATER  AIR- 
VALVE. 


An  automatic  air-valve  for  hot-water  radiators  is  shown  in 
the  sketch,  Fig.  89.  The  air  escapes  at  A,  the  orifice  being 
closed  by  the  float  /'"acting  on  the  lever  L.  So  long  as  only 
air  surrounds  the  float  it  sinks  and  keeps  the  orifice  open,  but 


FIG.  90. — FLANGED  EXPANSION-JOINT. 

as  soon  as  water  surrounds  it  it  rises  and  closes  the  orifice. 

62.  Expansion-joints. — In  the  erection  of  any  system  of 
piping  means  must  be  provided  so  that  the  elongation  of  the 


106  HEATING   AND    VENTILATING   BUILDINGS. 

pipe  due  to  expansion  will  not  cause  a  leak.*  For  all  ordinary 
purposes  of  heating  the  expansion  can  be  provided  for  by  trn 
use  of  elbows  and  right-angled  offsets,  of  such  length  that  th< 
expansion  will  simply  cause  one  pipe  to  slightly  unscrew  in  on 
or  more  joints.  This  requires  the  use  of  two  or  three  elbows 
and  so  causes  a  slight  increase  of  resistance  to  flow  due  to  fric 
tion  ;  but  it.  is  a  very  satisfactory  arrangement,  and  will  stan< 
for  years  without  developing  leaks,  even  with  high-pressur 
steam,  if  properly  erected. 

It  is  sometimes  necessary  to  provide  for  expansion  in 
long  line  of  straight  pipe,  in  which  case  expansion-joints  o 
some  kind  must  be  used.  The  ordinary  expansion-joint,  Fig 
90,  consists  of  a  sleeve  sliding  into  an  exterior  pipe,  providec 
with  a  stuffing-box.  This  joint,  when  heavy  and  providec 
with  a  catch  to  prevent  it  pulling  apart,  is  a  very  durable  anc 
satisfactory  construction.  The  packing  will  have  to  be  renevvec 
occasionally,  and  one  part  needs  to  be  solidly  anchored  t< 
prevent  motion. 

Expansion-joints  are  often  used  constructed  of  copper  pip 
in  form  of  a  U-shaped  bend  ;  also  of  one 
or  more  diaphragms  connected  to  each  othe 
at  the  edges  and  to  the  pipes  near  the  centre 
(Fig.  91).     The  copper  bend  is  always  satis 
factory.     The  last-named  device  works  very 
well  if  means  can  be  adopted  to  thoroughly 
drain  ofif  any  water  lodging  against  the  dia 

FIG.  91.— BUNDY       phragm.     If  used  in  a  horizontal  position 
ELASTIC  COUPLING.      and    Qn    large     pipes   it   is   likdy  to  gathe 

sufficient  moisture  to  form  a  water-hammer  that  may  product 
rupture  when  steam  is  turned  on. 

*  The  expansion  of  iron  is  one  part  in  148,000  of  length  per  degree.     This 
equivalent  to  about  1.45  inches  per  100  feet  in  changing  from   temperature  o 
freezing  to  boiling. 


CHAPTER   VI. 
RADIATORS  AND  HEATING  SURFACES. 

63.  Introduction. — The  amount    of    heat  which   will   pass 
I  through    various    kinds    of     radiating    surface     is    determined 
I  largely  by  experiment,  and  has  been  fully  discussed  in  Chapter 

IV.      In  this  chapter  we  will  consider  briefly  the  methods  of 
Iconstruction. 

When  steam  and  hot  water-heating  were  first  employed  the 
t  radiating  surface  consisted  almost  entirely  of  cast-iron  pipe  ar- 
|  ranged  in  horizontal  lines,  as  shown  in  Fig.  35,  page  88. 
I  With  the  invention  and  use  of  wrought-iron  pipe,  cast-iron  pipe 
I  was  superseded  by  coils  of  this  pipe,  and  at  a  somewhat  later 
I  day  largely  by  the  radiator  with  vertical  surfaces  made  either  of 
least  or  wrought  iron.  The  change  from  pipe  surfaces  to  radi- 
ators was,  no  doubt,  largely  due  to  the  attempt  to  economize 
1  space  in  the  room,  as  well  as  to  improve  the  appearance. 

64.  Radiating  Surface  of  Pipe. — Very  efficient  radiating 
faces  can  be  made  of  coils  of  piping  arranged  as  shown  in 

j  Figs.  92  and  93.  The  return-bend  coil  shown  in  Fig.  92  is 
made  by  connecting  return-bends,  Fig.  61,  page  96,  with  lines  of 
[Straight  pipe.  The  pipe  mostly  used  is  one  inch  in  diameter, 
although,  when  the  bends  are  numerous,  i^-  or  2-inch  pipe 
should  be  used  to  reduce  the  friction.  In  use  the  flow  is  con- 
tinuous, the  fluid  entering  at  the  top  and  thence  with  a  gradual 
descent  flowing  to  the  right  and  left  alternately,  finally  dis- 
charging at  the  bottom.  There  is  a  great  deal  of  friction  in 
coils  of  this  class,  and  air  is  likely  to  gather  in  the  bends  and 
stop  circulation.  The  writer  would,  therefore,  recommend  that 
they  be  employed  only  when  other  forms  will  not  answer. 

The  branch-tee  or  manifold  coil  is  constructed  by  connect- 
ing branch-tees  with  parallel  lines  of  pipe.  In  each  pipe-line 
one  or  more  elbows  must  be  placed  to  counteract  the  effect 

of  unequal  expansion. 

107 


io8 


HEATING   AND    VENTILATING   BUILDINGS. 


The  coil  may  be  arranged  on  a  flat  wall-surface  so  as  to 
form  a  mitre  branch-tee  coil  as  in  Fig.  93,  lower  part,  or  with 
both  branch-tees  at  one  end  and  elbows  and  nipples  at  the 
opposite  end  ;  the  fittings  at  ends  being  connected  by  pipes  hav- 
ing the  proper  pitch.  Such  a  construction  is  called  a  return 
branch-tee  coil,  see  upper  part  Fig.  93.  The  coil  may  be  ar- 
ranged on  two  sides  of  a  room  with  the  elbows  placed  in  the 
intervening  corner,  in  which  case  it  is  called  a  corner  coil. 

The  various  types  of  branch-tee  or  manifold  coils  as  de- 
scribed present  small  frictional  resistance  to  the  flow  of  steam 
or  water  and  give  satisfactory  service  for  either  steam  or  hot- 
water  heating. 


FIG.  92. — RETURN-BEND  COIL. 


FIG.  93. — BRANCH-TEE  MITRE  COIL  AND  RETURN-COIL. 

If  two  connections  are  used  the  steam  should  be  supplied 
at  the  highest  point  of  the  coil,  and  the  return  taken  off  at 
the  lowest;  if  one  connection,  steam  is  to  be  supplied  at 
the  lowest  point.  The  horizontal  portion  should  be  given  a 


RADIATORS  AND   HEATING   SURFACES.  1 09 

pitch  of  one  inch  in  ten  or  twelve  feet,  and  an  air  valve  or  cock 
should  be  connected  to  each  coil.  When  several  return-bend 
coils  are  grouped  together,  as  in  Fig.  94,  the  construction  is 
termed  a  box  coil.  This  has  all  the  faults  in  an  aggravated 
manner  that  were  ascribed  to  the  return-bend  coil,  and  in  addi- 
tion causes  a  loss  of  efficiency  due  to  close  grouping  of  surface. 


FIG.  94.— THE  Box  COIL. 

The  pipe  coils,  Figs.  92  to  94,  will  do  equally  well  for  steam 
j  or  hot-water  circulation. 

65.  Vertical  Pipe  Steam-radiators. — These  were  at  one 
j  time  used  extensively,  and  were  made  by  screwing  short  pieces 
j  of  vertical  pipe  into  a  cast-iron  base  and  connecting.the  pipes 

in  pairs  at  the  top  with  return-bends,  which  were  usually 
!  screwed  but  sometimes  pressed  on.  One  form  still  in  extensive 
j  use  was  made  by  screwing  pipes,  having  the  upper  end  closed 
land  provided  with  an  internal  diaphragm,  into  a  cast-iron  base. 
JThe  diaphragm  being  so  placed  as  to  produce  the  same  circula- 
ition  in  one  pipe  that  was  obtained  in  two  pipes  with  the  other 
'form. 

The  pipes  are  arranged  in  two  or  more  rows  as  necessary 
jto  secure  the  desired  radiating  surface.  In  early  radiators  of 
'this  class  the  base  was  provided  with  a  diaphragm,  and  each 
i return-pipe  was  trapped  by  a  cavity  filled  with  water  so  as  to 

insure  a  continuous  circulation  of  the  steam  through  each  pipe. 

In  some  of  the  recent  radiators  the  return-pipes  are  trapped 


1 


no 


HE  A  TING   AND    VENT7LA  TING   B  UILDINGS. 


as  explained  above  ;  but  in  nearly  every  case  the  base  is  entirely 
open  and  arranged  so  that  it  will  drain  freely,  no  attempt  beins 
made  to  force  circulation  in  any  direction.  In  some  of  tin 
recent  radiators  of  this  type  the  base,  instead  of  being  in  on< 
piece,  is  made  up  of  sections  connected  by  nipples,  so  that 

it  can  be  lengthene< 
or  shortened  at  pleas 
ure.  An  air-valve  must 
always  be  provide< 
with  these  radiatorsj 
the  best  location  foi 
which  is  at  about  on< 
third  the  height  of  tin 
radiator,  and  on  tl 
end  opposite  the  a< 
mission. 

The  wrought  -  iroi 
radiator  is  construct* 
in  nearly  every  case 
one-inch    pipe,    take 
of    such    length     th: 
there    is    one    squai 
foot  of  exposed  radiat 
FIG.  95.— PIPE  RADIATOR.  ing    surface    for 

pipe  in  the  radiator.     The  form  being  quite  regular  its  surfa( 
can  be  accurately  measured. 

66.  Cast-iron   Steam-radiators. — Cast-iron  radiators  ai 
now  mostly  used  in  direct  heating. 

Those  principally  used  have  vertical  radiating  surfaces,  ai 
are  made  either  by  screwing  loops  or  sections  into  a  holl< 
base  provided  with  the  requisite  openings,  or  by  connectii 
at  the  bottom  a  series  of  parallel  vertical  sections  by  nippli 
screwed  from  the  outside  or  inside  of  the  base.     The  first  foi 
of  radiators,  having  a  base  of  fixed  dimensions,  is  often  call< 
the   standard  form ;    the    latter,    which    can    be    increased 
diminished  in  length  by  adding  or  taking  off  sections,  is  callej 
a  sectional  radiator. 

The  radiator  is  in  some  instances  provided  with  a  flat  top 
which  is  held  in  place  by  screws,  but  the  greater  portion  of 


RADIATORS  AND   HEATING    SURFACES. 


Ill 


]  those  of  recent  design  have  a  highly  ornamented  surface  and 
r  are  used  without  top  or  screen  of 
I  any    description.       The    illustra- 
|  tions,  Figs.  93  to  106,  give  a  very 
I. fair   idea   of   the   appearance   of 

those  in  use.     They  are  painted 

in    various   colors,   enamelled   or 

bronzed,  as   may  be  required   by 

the  house  owners  or  architects. 

The  efficiency  of  direct  radia- 
tion   is   somewhat   increased    by 

painting  or  bronzing,  but  is  les- 
Isened  by  varnishing  or  enam- 
lelling:  but  that  of  indirect  is  not 
|:so  affected. 

These  radiators  are  made  in 
Igreat  variety  of  forms,  and  can 
I  be  had  of  such  shape  as  to  sur- 
1  round  columns,  or  fit  in  corners; 
land  of  almost  any  height  de- 
ll sired.  Some  of  the  radiators 

are   fitted  with  warming  closets. 


FIG.  96. 
STANDARD  CORNER  RADIATOR. 


i(See  Fig.  98,*  frontispiece,  for  illustration  of  styles  in  use.) 


FIG.  97. — SECTIONAL  RADIATOR.          FIG.  99.— CRESCENT  FI,UE  RADIATOR. 


With  permission  from  Heating  and  Ventilation. 


112  HEATING   AND    VENTILATING   BUILDINGS, 

The  sectional  radiators  are  in  many  cases  built  in  such  a 
manner  as  to  form  flues  for  the  passage  of  air  from  the  bottom \ 
to  the  top  of  the  radiator  for  the  purpose  of  increasing  the  air- 
heating  capacity.  Such  radiators  are  termed  flue  radiators 
(Fig-  99)- 


FIG.  100. — WHITTIER  EXTENDED  SURFACE  RADIATOR. 

Radiators  are  sometimes  built  with  projecting  fins  or  orna- 
ments of  cast  iron  for  the  purpose  of  greatly  extending  thet 
surface  in  contact  with  the  air.     Such  a  radiator  is  termed  am 
extended  surface  radiator,  and  is  now  little  used  for  direct  heat-! 
ing  (Fig.  i oo). 

The  radiators  in  principal  use  are  constructed  as  described, 
but  radiators  have  been  built  by  many  other  methods  and  ini* 
many  other  shapes.     They  have  been  constructed  of  one  soliql 
casting,  and  by  uniting  sections  of  various  forms  by  bolts  andj 
packed  joints. 

67.  Hot-water    Radiators. — Hot-water     radiators    differ  j 
essentially  from    the    steam-radiators   in    having  a  horizontal 
passage  at  the  top  as  well  as  at  the  bottom.     This  construction  ! 
is  necessary  in  order  to  draw  off  the  air  which  gathers  at  the  top 
of  each  loop  or  section.     Aside  from  this  the  construction  may 
be  the  same  in  every  particular  as  that  for  steam-radiators  ;  in 


RADIATORS  AND   HEATING   SURFACES.  113 

genera,  the  hot-water  radiator  will  be  found  well  adapted  for 


FIG.  101. — SECTION  OF  HOT-WATER  RADIATOR. 


, 


FIG.  102.— SECTIONAL  HOT-WATER  RADIATOR. 

team    circulation,   being   in    some   respects   superior  to   trie 
rdinary  form. 


114 


HEATING   AND    VENTILATING   BUILDINGS, 


Many  of  the  hot-water  radiators,  as  shown  in  Fig.  101, 
are  made  with  an  opening  at  the  top 
for  the  entrance  of  water  and  at  the 
bottom  for  its  discharge,  thus  insuring 
a  supply  of  hot  water  at  the  top  and  of 
colder  water  at  the  bottom. 

Some  of  the  hot-water  radiators  are 
constructed  with  a  cross-partition  so  that 
all  water  entering  passes  at  once  to  the 
top,  from  which  it  may  take  any  passage 
toward  the  outlet. 

The  hot-water  radiator,  is  however, 
usually  made  with  continuous  passages 
at  top  and  bottom,  and  the  warm  water  is 
supplied  at  one  side  and  drawn  off  on 
the  other,  as  shown  in  Figs.  102  and  105  (right  hand).  The 
action  of  gravity  is  depended  on  for  making  the  hot  and  lighter 
water  pass  to  the  top  and  the  cold  water  to  sink  to  the  bottom 
and  flow  off  in  the  return. 


FIG.  103.*— RADIATORS 
WITH  TOP  AND  BOT- 
TOM CONNECTIONS. 


FIG.  104. — SECTIONAL  HOT-WATER  RADIATOR. 


Hot-water  radiators  are  also  made  by  joining  vertical 
pipe  sections  with  nipples  at  top  and  bottom,  as  shown  in 
Fig.  1 06. 


*  Heating  and  Ventilating  of  Residences,  by  Willet. 


RADIATORS  ANL    HEATING   SURF  A    ES.  11$ 


(STEAM.)  (HOT-WATER.) 

FIG.  105.— SECTION  OF  CAST-IRON  RADIATOR. 


FIG.  1 06. — SECTIONAL-PIPE  HOT-WATER  RADIATOR. 


HEATING   AND    VENTILATING   BUILDINGS. 

68.  Direct-indirect  Radiators. — Radiators  arranged  with 
a  damper  under  the  base  and  located  so  that  air  from  the  out- 


Fio.  107. — DIRECT-INDIRECT 
RADIATQR  IN  POSITION. 


FIG.  loS. — DIRECT-INDIRECT  RADIATOR. 


side  will  pass  over  the  heating  surface  before  entering  the  room 
are  often  used  to  improve  the  ventilation.  The  surface  of  these 
radiators  should  be  about  25  per  cent  greater  than  that  of  a 
direct  radiator  for  heating  the  same  space.  The  styles  and 
kinds  either  for  steam  or  hot  water  are  the  same  as  the  direct. 
69.  Indirect  Heaters. — Radiators  which  are  employed 
to  heat  the  air  of  a  room  in  a  passage  or  flue  which  supplies 
air  are  termed  indirect.  These  heaters  are  made  in  various 
forms,  either  of  pipe  arranged  in  return  bend  or  in  manifold  coils, 
as  in  Fig.  93,  or  of  cast-iron  sections  of  various  forms  united 
in  different  ways.  When  cast-iron  surfaces  are  used,  they  are 
generally  covered  with  projections  like  the  extended  surface 
radiator.  The  sections,  or,  as  they  are  sometimes  called,  the 
stacks  for  indirect  heating,  are  usually  held  together  by  bolts. 
The  joints  being  formed  by  inserting  packing  between  faced 
surfaces.  The  sections  are  sometimes  united  by  nipples  screwed 
into  branch-tees  above  and  below,  as  shown  in  Fig.  109,  which 
is  an  excellent  form  for  hot-water  circulation. 


RADIATORS  AND    HEATING   SURFACES. 
Indirect  radiators  should  be  placed  in  a  chamber  or  box  as 


FIG.  109. — INDIRECT  HEATING  SURFACE. 


vent 


FIG.  no — INDIRECT  PIPE  COIL. 

nearly  as  possible  at  the  foot  of  a  vertical  flue  leading  to  the 
room  to  be  heated. 

Air  is  admitted  through 
a  passage  from  the  out- 
side provided  with  suit- 
able dampers  to  a  point 
beneath  the  indirect 
stacks.  It  is  taken  off 
generally  on  the  opposite 
side,  and  directly  into  the 
flue  leading  into  the  room 
to  be  heated. 

The  chamber  surround- 
ing     the      indirect       radi-       FIG.  III.-ARRANGEMENT  OF  INDIRECT 
ator   is    usually    built    of  HEATER. 

a  casing  of  matched  wood,  as  in  Fig.  ill  and  Fig.  112,  sus- 


nS 


HEATING   AND    VENTILATING   BUILDINGS. 


pended  from  the  ceiling  of  the  basement,  and  lined  inside  with 

bright  tin ;  but  a  small  chamber 
of  masonry  at  the  bottom  of  a 
flue  is  a  better  and  more  durable 
construction.  The  flue  leading 
from  the  chamber  is  of  masonry 
or  galvanized  iron  ;  that  supply- 
ing the  cold  air,  of  matched  wood 
and  sheet  iron.  There  should  be  a 
door  in  the  chamber  so  that  the  in- 
direct heater  can  be  examined  and 
cleaned  when  required.  It  is  often 
of  advantage  to  have  a  passage 
and  deflecting  damper  so  arranged 
that  air  can  be  drawn  into  the 

FIG.  112. — ARRANGEMENT  OF  INDI- 
RECT HEATING  SURFACE. 

room     for    ventilation     without 
passing  over  the  heater. 

The  registers  for  admitting 
the  heated  air  into  the  rooms 
can  be  located  as  desired,  either 
in  the  walls  or  the  floor ;  for 
ventilation  purposes  it  is  prefer- 
able to  admit  the  air  near  the 
ceiling,  and  as  shown  in  Fig.  113. 
The  size  of  registers  and  air- 
flue  will  be  given  in  Chapter 
XIII. 

Setting  of  Indirect  Heaters. — 
The  indirect  heating-surface  is 
supported  usually  by  bars  of  iron 
or  pieces  of  pipe  held  in  place  by 
hangers  fastened  at  the  ceiling 
(Fig.  1 1 1).  This  heater  should  be 
set  so  as  to  give  room  for  the 

freest  possible  circulation  of  air,  and  so  that  all  parts  will  be  at 
least  ten  inches  from  top  or  bottom  of  casing,  and  arranged  so 


FIG.   113. — INDIRECT  HEATER 

ARRANGED   FOR    VENTILATION. 


RADIATORS  AND    HEATING'  SURFACES. 


that  no  air  can  pass  into  rooms  without  being  warmed.  An 
automatic  air-valve  should  be  used  to  remove  the  air  from 
the  sections  of  the  heater. 

If  the  sections  are  of  proper  form,  one  connection  will  be 
sufficient  for  steam  ;  but  in  nearly  every  case  two  connections, 
one  for  the  supply  and  one  for  the  discharge,  will  be  re- 
quired for  water  circulation. 

70.  Proportions  of  Parts  of  Radiators. — There  is  great 
difference  regarding  the  relative  volume  of  radiators  of  differ- 
ent make  as  compared  with  the  surface ;  but  the  practice  is 
quite  uniform  as  regards  the  sizes  of  supply-pipes  for  either 
steam  or  hot  water.  Because  of  the  high  efficiency  of  a  radiat- 
ing surface  formed  of  one-inch  horizontal  pipe,  it  has  been 
argued  that  this  should  form  a  standard  for  relation  of  contents 
to  surface.  It  is  seen,  however,  by  consulting  the  tests  given 
in  Chapter  IV,  that  inch-pipe  vertical  radiators  are  not  more 
efficient  than  cast-iron  radiators  with  larger  volume  ;  so  that 
it  is  doubtful  if  the  relative  ratio  of  volume  to  surface  is  of 
importance. 

It  is  of  importance  that  the  steam  or  water  should  circulate 
through  the  radiators  with  the  least  possible  friction,  and  that 
in  the  case  of  steam-radiators  the  base  should  be  of  such  a  form 
as  to  perfectly  drain  ;  otherwise  the  water  which  remains  in  will 
be  certain  to  cause  the  disagreeable  noise  and  pounding  known 
as  water-hammer. 

The  following  table  gives  the  standards  which  are  almost  uni- 
versally adopted  by  the  different  makers  for  the  size  of  inlet 
and  outlet  to  the  direct  radiators ;  those  for  indirects  are  to  be 
taken  one  size  larger  : 


Size  of  Radiator, 
Sq.  Ft. 

Diameter  of  Openings. 

Two  Openings. 

One  Opening. 

o  to    50 
50  to  125 
125  to  2OO 
200  tO  300 

i    inch. 
i£  inches, 
i*        " 

2 

i£  inches, 
i*        " 

2 
2k 

CHAPTER   VII. 

STEAM-HEATING   BOILERS   AND   HOT-WATER   HEATERS. 

71.  General  Properties  of  Steam— Explanation  of  Steam- 
tables. — Steam  has  certain  definite  properties  which  always 
pertain  to  it  and  distinguish  it  from  the  vapor  of  other  liquids 
than  water. 

Steam,  at  any  given  pressure  above  a  vacuum,  possesses  a 
definite  temperature.     The  atmospheric  pressure  is  different  at 
different  localities  and  for  different  conditions  of  the  weather, 
thus  causing  slight  changes  in  temperature  of  the  boiling-point. 
The  pressure   which    is    read   by  any  steam-gauge  is  that  in 
excess  of  the  atmosphere  ;  the  pressure  which  is  given  in  the 
steam-tables  is  that  which  is  reckoned  from  a  perfect  vacuum,  \ 
and  is  usually  called  absolute  ;  hence,  in  order  to  use  the  steam-  \ 
table  which  is  given  in  the  back  of  the  book,  the  pressure  as 
determined  by  a  steam-gauge  reading  must   be   increased  by 
the  atmospheric  pressure.     The  atmospheric  pressure  is  given! 
accurately  by  a  barometer,  but  it  will  be   sufficiently  accurate,  I 
for  most  cases,  to  consider  it    as    14.7  pounds.     To    use  the 
table  add  this  quantity  to  the   gauge-reading  and  the  result  j 
will  be  the  absolute  pressure.     For  approximate  purposes  the] 
atmospheric  pressure  maybe  considered  as   15  pounds.     The  j 
steam-tables  referred  to  give,  in  the  first  column,  the  pressure! 
above  a  vacuum  ;  in  the  second  column,  the  temperature  Fahr-| 
enheit ;  in  the  third,  the  heat,  expressed  in  heat-units,  required 
to  raise  one  pound  of  water  from  zero  Fahrenheit  to  the  re-j 
quired  temperature.     If  the;  specific  heat  of  water  were  unity 
at  all  temperatures,  the  heat  contained  in  one  pound  of  water' 
would    be    numerically  the    same   as  the  temperature.      The 
difference  is  not  great  in  any  case. 

The  fourth  column  gives  the  value  in  heat-units  of  the  la- 
tent heat  of  evaporation  for  each  pound  of  steam.  This  quan  J 


S  TEAM-HE  A  TING  BOILERS.  —HO  T-  WA  TER  HE  A  TERS.      1  2  1 

tity  expresses  the  amount  of  heat  which  is  stored,  without 
change  of  temperature  or  pressure,  during  the  physical  change 
of  condition  from  water  to  steam  ;  and  it  has  been  termed 
latent  because  it  cannot  be  measured  by  a  thermometer  (see 
Art.  13,  page  15).  It  will  be  noted  that  this  quantity  is  rela- 
tively large  as  compared  with  the  sensible  heat.  It  is  of  im- 
portance, since  it  expresses  the  amount  of  heat  which  is  con- 
tained in  one  pound  of  steam  in  excess  of  that  in  one  pound  of 
water  at  the  same  temperature. 

The  fifth  column  gives  the  total  heat  contained  in  one 
pound  of  steam  ;  this  is  the  sum  of  the  sensible  and  latent  heat. 

The  sixth  column  gives  the  weight  in  pounds  of  one  cubic 
foot  of  steam  for  various  pressures.  In  many  instances  steam- 
tables  are  arranged  so  as  to  give  the  heat  in  one  pound  of 
steam  above  32°  Fahr.,  the  freezing-point  of  water,  instead  of 
above  zero. 

It  should  be  noted  that  the  temperature  of  steam  corre- 
sponding to  different  pressures,  as  given  in  column  (2),  is  also 
the  boiling-point  of  water  corresponding  to  the  same  pressure. 

As  the  temperature  and  absolute  pressure  of  steam  al- 
ways bear  definite  relation  to  each  other,  it  is  quite  evident 
that  a  steam-table  could  be  arranged  giving  the  properties  of 
steam  from  measurements  of  .temperature.  This  is  generally 
not  so  convenient  as  the  present  arrangement.  If  tempera- 
tures are  known,  the  corresponding  pressure  can  be  determined 
by  inspection  and  interpolation  in  the  present  table. 

72.  General   Requisites  of   Steam-boilers.  —  The  steam- 

boiler  is  a  closed  vessel,  which  must  possess  sufficient  strength 

to  withstand  the  pressure  to  which  it  may  be  subjected  in  use  ; 

j  but  it  may  have  almost  any  form,  and  may  be  constructed  of 

j  various  materials. 

It  is  used  in  connection  with  a  furnace,  from  which  the  heat 
required  for  evaporation  is  obtained  by  combustion  .of  fuel. 
The  heat  is  received  on  the  surface  of  the  boiler,  and  passes 
by  conduction  through  the  metallic  walls  to  the  water  or 
steam.  The  surface  which  receives  this  heat  is  called  heating 
surface,  and  is  partly  situated  so  as  to  receive  the  direct  or 
radiant  heat,  and  partly  located  so  as  to  receive  the  convected 
or  indirect  heat  from  the  gases  only.  The  heating  surface  in 


UNIVERSITY 


122  HEATING   AND    VENTILATING   BUILDINGS. 

most  modern  boilers  is  made  relatively  great,  as  compared  with 
the  cubic  contents,  by  the  use  of  tubes  containing  water  or 
heated  gases,  or  by  subdividing  the  boiler  so  as  to  make  the 
surface  large  with  respect  to  the  cubic  contents  and  weight. 
The  steam  generated  rises  in  the  shape  of  bubbles  through 
the  water  in  the  lower  part  of  the  boiler,  and  is  liberated 
from  the  surface  of  the  water  at  the  water-line. 

The  power  of  the  boiler  depends  upon  the  amount  and 
form  of  heating  surface,  upon  its  capacity  for  holding  water 
and  steam,  and  upon  the  extent  of  fire-grate  surface.  Its 
economy  depends  upon  the  relative  proportions  of  these,  and 
the  character  and  amount  of  fuel  burned.  Its  ability  to  pro- 
duce dry  steam  depends  upon  the  circulation  of  its  liquid 
contents,  and  also  upon  the  extent  of  surface  at  the  water-line. 

For  safety,  the  boiler  must  be  provided  with  safety-valve, 
pressure  and  water  gauges.  For  convenience  automatic 
damper-regulators,  water-feeding  apparatus,  etc.,  are  desirable. 

73.  Boiler  Horse-power. — As  a  boiler  performs  no  actual 
work,  but  simply  provides  steam  for  such  purposes,  a  boiler 
horse-power  is  entirely  an  arbitrary  quantity,  and  may  be 
transformed  into  a  lesser  or  greater  amount  of  work,  as  the 
character  of  the  engine  which  uses  the  steam  varies. 

The  standard  established  by  the  Committee  of  Judges  at 
the  Centennial  Exhibition  in  1876  as  a  boiler  horse-power  has 
been  universally  adopted,  and  would,  no  doubt,  in  absence 
of  other  stipulations,  constitute  a  legal  standard  of  capacity. 
This  committee  defined  a  boiler  horse-power  as  the  evapora- 
tion of  30  pounds  of  water  from  feed-water  at  100°  Fahr.  into 
steam  at  70  pounds  pressure ;  this  is  equivalent  to  the  evapo- 
ration of  34.5  pounds  of  water  from  a  temperature  of  2I2C 
Fahr.  into  steam  at  atmospheric  pressure.*  Engines  require 
from  12  to  40  pounds  of  steam  per  horse-power  per  hour, 
depending  upon  the  grade  or  class  to  which  they  belong ; 
hence  the  steam  required  to  perform  one  horse-power  of 
work  in  an  engine  bears  no  definite  relation  to  a  boiler  horse- 
power. 

'••'The  condition  of  evaporating  from  water  at  212°  into  steam  at  the 
same  temperature  will  be  referred  to  hereafter  as  evaporation,  without  other 
qualification. 


S  TEA  M-HEA  TING  BOILERS.— HO  T-  IV A  TER  HE  A  TERS.     1 2  3 

Since  the  evaporation  of  one  pound   of  water  from  and  at 
212°  Fahr.  requires  966  heat-units,  one  boiler  horse-power  is 
|  equivalent  to  33,327  heat  units. 

For  heating  purposes  a  more  convenient  standard  of  power 
j  is  the  square  foot  of  radiating  surface.  Each  square  foot 
\  of  direct  steam-radiating  surface  gives  off  270  to  330  heat-units 
j  per  hour  when  the  difference  of  temperature  is  150  degrees  (see 
Art.  51),  which  is  that  usually  existing  in  low-pressure  steam- 
heating.  About  two  thirds  as  much  is  given  off  by  one  square 
j  foot  of  hot-water  radiating  surface.  As  the  evaporation  of  one 
I  pound  of  water  requires  966  heat-units,  there  is  needed  about 
tone  third  of  a  pound  of  steam  for  each  square  foot  of  steam- 
Lradiating  surface  per  hour,  hence  one  boiler  horse-power  will  be 
1  sufficient  to  supply  somewhat  more  than  100  square  feet  of 
j  direct  radiating  surface;  that  is,  we  can  consider  the  boiler 
j  horse-power  as  equivalent  to  100  square  feet  of  direct  steam 
"\  radiation,  with  sufficient  allowance  to  meet  ordinary  losses. 

74.  Relative  Proportions  of  Heating  to  Grate  Surface.— 
I  The  relative  amount  of  grate  surface  and  heating  surface  re- 
\  quired  in  a  steam-boiler  depends,  to  a  large  extent,  upon  the 
I  nature  and  amount  of  coal  burned  per  unit  of  time.     That  part 
of  the  heating  surface  which  is  close  to  the  fire  and   receives 
directly  the  radiant  heat  is  much  more  effective  than  that  which 
is  heated  by  contact  with  hot  gases  only  ;  but  it  will  be  found 
\  that  considerable  indirect  heating    surface  will  in  every  case 
be  required,  in  order  to  prevent  excessive  waste  of  heat  in  the 
chimney.     Power-boilers  have  been  rated  for  a  long  time  not 
I  on  their  actual  capacity,  but  on  the  amount  of  heating  surface  ; 
j  and  this  would  seem  to  be  a  fair  standard  of  rating  for  heating- 
boilers.     It  is  the  general  practice  to  consider   11.5  square  feet 
j  of  heating  surface  in  water-tube  boilers  or  15  square  feet  in 
plain  tubular  boilers  as  equivalent  to  one  horse-power. 

The   actual  power  of    the  boiler  depends  more  upon  the 

method  and  management  of  the  fires  than  upon  the  size  ;  and 

|  either  of  the  above  classes  of  boilers  can  be  made  to  develop 

\  under  favorable  circumstances   from   two  to  three  times  the 

capacity  for  which  they  are  rated. 

A  rating  of  15  sq.  ft.  of  heating  surface  to  one  horse-power 
requires  an  evaporation  of  2.3  Ibs.  of  water  per  square  foot  of 


124  HEATING   AND    VENTILATING   BUILDINGS. 

heating  surface  per  hour,  and  a  rating  of  11.5  sq.  ft.  per  hors 
power   requires  an  evaporation   of   3   Ibs.     Experience    for 
number  of  years  with  power-boilers — 20  horse-power  and  largei 
— indicates  these  proportions  to  be  safe  ones  and  to  result 
durable  construction.  With  the  small  boilers  often  used  in  house-1 
heating  the  waste  due  to  loss  of  heat  from  the  heating  surfaces, 
imperfect  combustion,  and  bad  management  generally  are  much 
greater,  so  that  it  is  necessary  to  use  boilers  somewhat  larger 
than  would  be  required    by  the    data  given.       Knowing   the; 
amount   of  coal  per  hour  and  the  evaporation  per  pound  of 
coal,  we  could  readily  calculate  the  steam  produced  in  pounds.) 
This  result  multiplied  by  three   would  give  very  closely  the 
extent  of  direct  radiating  surface  which  could  be  supplied. 

With  perfect  combustion  and  no  waste,  one  pound  of  pure! 
carbon  would  evaporate  about  15  Ibs.  of  water;  all  coal  con- 
tains considerable  ash  and  refuse,  on  account  of  which  the  best! 
results  are  lower,  so  that  one  pound  of-  best  anthracite  coal; 
might  evaporate  13  Ibs.  of  water,  and  of  bituminous  from  10  toj 
14  Ibs.  Our  average  evaporation  in  power-boilers  is  probably! 
about  9  Ibs.  when  served  by  good  firemen,  and  in  heating- 
boilers  it  is  usually  much  less,  not  because  of  faulty  construc-1 
tion  of  the  boiler,  but  for  lack  of  proper  and  careful  manage-; 
ment.  The  amount  of  coal  burned  per  square  foot  of  grate; 
per  hour  is  rarely  less  than  15  Ibs.  with  power-boilers,  and  in 
some  cases  is  very  much  greater,  but  is  usually  less  than  10  IbsJ 
and  is  sometimes  as  small  as  3  or  4  with  heating-boilers. 

For  these  reasons  no  hard  and  fast  rule  can  be  given  for  thej 
proportions  of  different  boilers  and  heaters,  and  a  considerable- 
variation  may  be  expected  in  the  relative  proportions  of  heat-: 
ing,  grate,  and  radiating  surface  existing  in  successful  plants. 
By  making  allowance  for  the  probable  loss  of  efficiency  in  small 
heaters,  we  can,  by  starting  with  the  proportions  which  have! 
been  found  to  be  satisfactory  in  large  plants  where  power-! 
boilers  are  used,  compute  a  table  which  will  be  based  on  thej 
results  of  actual  trial  and  experiment.  This  table  will  give  di- 
mensions which  are  well  within  the  limits  of  those  in  actual  usej 
but  it  should  not  be  inferred  that  satisfactory  plants  cannot  bJ 
constructed  with  proportions  varying  ten  or  twenty  per  cent- 
from  those  given.  The  table  is  computed  from  the  follow i™ 


S  TEA  M-HEA  TING  BOILERS.  —HO  T-  WA  TER  HE  A  TERS.      1 2  5 


data,  which  were  assumed  for  reasons  already  stated  :  ist,  one 
pound  of  steam  will  supply  3  sq.  ft.  of  direct  steam-radiating 
surface;  2d,  15  sq.  ft.  of  heating  surface  (one  horse-power) 
in  the  boiler  will  supply  100  sq.  ft.  of  steam  or  150  sq.  ft. 
of  hot-water  direct  radiating  surface,  when  the  boilers  con- 
tain 450  sq.  ft.  and  above  of  heating  surface  ;  $d,  loss  in  ef- 
ficiency assumed  to  be  10  per  cent  for  reduction  in  capacity  of 
50  per  cent ;  4th,  rate  of  evaporation  for  steam-boilers  is  taken 
so  as  to  agree  with  the  experience  of  the  writer.  Two  cases 
are  considered  in  the  table  :  (A)  when  the  rate  of  coal  consump- 
tion is  10  Ibs.  and  (B)  when  the  rate  of  coal  consumption  is 
8  Ibs.  per  sq.  ft.  of  grate  per  hour.  The  latter  in  every  case 
gives  a  somewhat  larger  grate,  and  for  hot-water  heating  is  no 
doubt  to  be  preferred. 

PROPORTION   OF    PARTS   OF   STEAM-HEATING    BOILERS. 


Radiating  Surface,  Square  Feet. 

250 

500 

750 

1000 

1500 

2OOO 

3000 

4000 

5000  ;  7500 

10000 

Nominal  horse-power  

2  5 

5 

7.5 

10 

15 

20 

30 

40 

5°        75 

IOO 

Ratio  radiating  to  heating  surface.  .  . 

4-5 

5-4 

5-6 

6 

6.2 

6.7 

6.9 

f  j.  h. 

J. 

Probable  evaporation  per  Ib.  coal..  . 
Pounds  of  steam  per  sq.  ft.  grate  (A) 
"         "      (B, 

5-5 

55 

44 

5-7 

6 
60 

48 

6-5 
65 

S2 

*7 

5 

7-5 

£ 

8 
80 
64 

ti 

68 

9     !     9-5 
9o     |  95 
72     1  76 

10 
IOO 

80 

Ratio  radiating  to  grate  surface  (A)  165 

171 

1  80 

195 

2IO 

225 

240 

255 

270     [285 

300 

(B) 

132 

138  1144  JI5& 

1  08 

1  80 

192 

204 

216      228 

240 

heating  to  grate  surface  (A).. 

36.5 

33-2 

33-2 

34-8 

35 

36.2 

36-5 

37 

38.5]  !  £;|* 

33-3* 

'  (B).. 

28.5 

27 

26.7 

27.7 

28 

29 

28.5 

29.6 

30.  s  -j  i  l2/^ 

26.'?* 

Heating  surface,  sq.  ft  

55 

98 

138 

178 

250 

322 

447 

580 

710    j  j    I07^ 

1430 

1111* 

Grate  surface  sq   ft  (A) 

r    68 

8  o 

41     (B)  

1.88 

3.88 

5-4 

i 

6.77 

0 

8.92 

II  .2 

T5-5 

iQ-S 

23.2     i  32.5 

41-5 

Diameter  safety-valve,  inchest  .... 

7 

2.25 

10 

2.502.75 

II         12 

3 
15 

3-25 
17 

3-5 
»9 

4 
23 

4           2  of  3 

25         ,   28 

2  of  4 

34 

"         smoke-flue,  inches  

HOT-WATER  HEATERS. 


itio  radiating  to  heating  surface. 
"  grate(A) 

(B) 

'       heating  to  grate  (A) 


'     (B) 

Heating  surface,  sq.  ft 

Grate  surface,  sq.  ft.  (A) 

"      (B) 

Diameter  smoke-flue,  inches 


6.8 

7.6 

8.1 

8-4 

9 

9-3 

10 

10.4 

10.5 

247 

256 
207 

270 
216 

292 
232 

315 
252 

337 
270 

360 
288 

•382 
306 

405 
324 

360 

33-2 

33-2 

34-8 

35 

36-2 

36.5 

37 

38.5 

28.5 

27 

26.7 

27.7 

28 

29 

28.5 

29.6 

30.8 

36.5 

1% 

9i-5 

2  .7  c 

118 

3<7C 

166 

215 

5.O 

296!  385 

8.  2  T<->.,« 

470 

1.25 

2*58 

3-6 

•  /D 

4.25 

4*  75 
5-9 

•y 
7-1 

10.3 

13 

15-3 

7 

10 

11 

12 

15 

17 

19 

23 

25 

10.5 
13-5* 

427 

342 
40-5 
31-5 

s* 


a-5 


10.5 

13  5* 

450 

360 
42.5 
33-3 
34-5 
26.5* 

905 

22.2 

27-5 

34 


*  Water-tube  boiler. 

f  Safety-valves  by  Board  of  Trade  rule. 
5  and  10  Ibs. 


Smaller  boilers  figured  to  blow  at 


126 


HEATING   AND    VENTILATING   BUILDINGS. 


A  very  interesting  comparison  of  relative  proportions  of 
various  boilers  used  for  steam-heating  was  made  by  S.  Q.  Hayes 
from  published  statements  of  manufacturers  in  Heating  and 
Ventilation,  April  15,  1895,  and  from  which  the  following  table 
is  abstracted.  It  will  be  seen  that  the  proportions  of  radiating 
surface  to  grate  surface  agree  well,  when  the  fact  is  considered 
that  many  published  statements  are  far  from  accurate,  with  the 
values  recommended  for  a  coal  consumption  of  8  Ibs.  of  coal 
per  hour,  per  square  foot  of  grate. 

TABLE    SHOWING    PROPORTIONS     CLAIMED    BY    MAKERS   FOR 
STEAM-HEATING   BOILERS. 


Steam-heating  Boilers. 

Ratio  Radiating 
to  Grate  Surface. 

Ratio  Heating 
to  Grate  Surface. 

Ratio  Radiating  to 
Heating  Surface. 

Square  Foot  of  Radiation. 

250 

500 

750 

1500 

2000 

250 

500 

'5° 

1500 

2000 

250 

5oo 

750 

1500 

2OOO 

KIND  OF  BOILER. 

Tubular,  vertical,  magazine.... 
"        surface  
"                "        steel  
Vertical  shell,   drop-  and  fire- 
tubes.  
Pipe  boiler  
Pipe-coil  boiler  
Drop-tube,  wrought  iron  
4           '      cast-iron  magazine. 
"        surface.  . 
'          '      magazine.  
4           '      wrought  iron  

Coil  and  drop-tube  .. 
Horizontal  sectional.  

Vertical  sectional  

134 
i  So 
170 

140 
i  So 
75 
185 
198 
240 

rts 

i5o 

1  60 

i7o 
130 

130 

,67 
1  90 

'47 

170 
1  80 
75 
*9S 
172 
186 

rSo 

«6j 

150 
240 

',>(  JO 

i  So 
H7 

II  2 

'35 
US 

192 

167 
200 
138 

170 

i  So 
75 
205 
204 
224 
170 

200 

216 

200 
I38 
I30 
150 
IS'? 
200 

1  80 
I90 

180 
180 

75 

228 
22O 

'180 
75 

23 

30 
30 

26 

20 
25 
42 

36 

43 

35 

22 
32 

3° 
32 
24 

32 
23 

I 

32 
36 
37 

25 
44 
35 
-36 
24 
24 
3° 
23 
32 

23 
33 
25 

30 
25 
25 
33 
35-7 
40 
27 

24 
34 

P 

I-8 

56 

i-3 

7-4 
6 

7-7 
6 

6  ' 

7 
'*-3 

'&" 

6-3 
6 

3° 
27 

3° 

I., 

3 

4-4 

5-5 
5-4 

« 

4 
4 
5 

5-7 

e" 

5-3 

6-5 
3 

^ 

5-8 
5 

^•5 

5 

5-7 
5 
5 

5 
5-3 

f;-5 

5-5 

1 

5-7 
5-7 
5 

6.2 

6 
6 
4.7 
5-7 
6 

7 
6 

i'7 
'£5 

6 

I'3 

6-5 

6 
5-7 
5-7 
6 

32-7 
23 

22 

170 

210 

216 

300 

130 
155 
163 
230 

'180 
230 

1 

26 
25 
24 
25 

20 

33 

1 

36 

27 

'55 
167 
250 

3° 

1  6 
28 

24 
25 
25 
37 

24 
30 
40 

41        sectional,  tubular  

75.  Water  Surface— Steam  and  Water  Space.— The 
surface  on  the  water-line  from  which  ebullition  takes  place 
should  be  so  large  that  the  velocity  of  steam  will  not  be  great 
enough  to  project  particles  of  water  into  the  main  steam-pipes. 
Practice  is  variable  in  this  respect  ;  in  successful  plants  it 
will  be  found  that  from  one  third  to  one  square  foot  of  surface 
is  provided  per  horse-power  or  per  100  square  feet  of  radiating 
surface.  The  greater  this  surface  the  less  water  will  be  carried 
out  of  the  boiler  with  the  steam,  other  things  being  equal. 

There  is  much  variation  in  the  amount  of  water  and  steam 
space  provided  in  various  kinds  of  boilers :  in  the  fire-tube  and 


STEAM-HE  A  TING  BOILERS.— HO  T-  WA  TER  HE  A  TERS.      1 2/ 

shell  boilers  there  is  much  more  space  than  in  water-tube  and 
sectional  boilers.  A  large  amount  of  water  and  steam  absorb 
the  heat  slowly,  but  on  the  other  hand  they  require  less  fre- 
quent attention  and  are  more  regular  in  operation.  The  fol- 
lowing rules  have  been  given  : 

Tredgold*  states  that  the  volume  of  steam  space  should 
be  sufficient  to  prevent  variations  in  pressure  exceeding  I  in 
30,  by  irregular  use. 

The  Artisan  Club  allowed  5  cubic  feet  of  water  space  and 
3.2  cubic  feet  of  steam  space  per  horse-power  for  Cornish 
boilers. 

In  the  ordinary  tubular  boilers  to-day  there  will  be  -found 
about  2.0  cubic  feet  of  water  and  i.o  cubic  foot  of  steam  per 
horse-power,  and  about  one  third  the  above  amounts  for  the 
water-tube  boilers. 

76.  Requisites  of  a  Perfect  Steam-boiler. — The  late  Mr. 
George  H.  Babcock  of  Plainfield,  N.  J.,  gives  as  the  results 
of  his  experience  the  following  requisites  for  a  perfect  steam- 
boiler  for  power  purposes : 

ist.  The  best  materials  sanctioned  by  use,  simple  in  con- 
struction, perfect  in  workmanship,  durable  in  use,  and  not  liable 
to  require  early  repairs. 

2d.  A  mud-drum  to  receive  all  impurities  deposited  from 
the  water  in  a  place  removed  from  the  action  of  the  fire. 

3d.  A  steam  and  water  capacity  sufficient  to  prevent  any 
fluctuation  in  pressure  or  water-level. 

4th.  A  large  water  surface  for  the  disengagement  of  the 
steam  from  the  water  in  order  to  prevent  foaming. 

5th.  A  constant  and  thorough  circulation  of  water  through- 
out the  boiler,  so  as  to  maintain  all  parts  at  one  temperature. 

6th.  The  water  space  divided  into  sections,  so  arranged 
that  should  any  section  give  out,  no  general  explosion  can 
occur,  and  the  destructive  effects  will  be  confined  to  the 
simple  escape  of  the  contents ;  with  large  and  free  passages 
between  the  different  sections  to  equalize  the  water  line  and 
pressure  in  all. 

/th.  A  great  excess  of  strength  over  any  legitimate  strain  ; 
so  constfucted  as  not  to  be  liable  to  be  strained  by  unequal 


*  Thurston's  Steam-boilers. 


128  HEATING  AND    VENTILATING   BUILDINGS. 

expansion,  and,  if  possible,  no  joints   exposed   to   the  direct 
action  of  the  fire. 

8th.  A  combustion-chamber,  so  arranged  that  the  combus- 
tion of  gases  commenced  in  the  furnace  may  be  completed  be- 
fore they  escape  to  the  chimney. 

9th.  The  heating  surface  as  nearly  as  possible  at  right 
angles  to  the  currents  of  heated  gases,  and  so  as  to  break  up 
the  currents  and  extract  the  entire  available  heat  therefrom. 

10th.  All  parts   readily  accessible  for  cleaning  and  repairs.' 
This  is  a  point  of  the  greatest  importance  as  regards  safety 
and  economy. 

nth.  Proportioned  for  the  work  to  be  done,  and  capable  of 
working  to  its  full  rated  capacity  with  the  highest  economy. 

1 2th.  The  very  best  gauges,  safety-valves,  and  other  fix- 
tures. 

The  same  requirements  apply  equally  well  to  a  boiler  for 
heating,  but  the  relative  importance  of  the  various  require- \ 
ments  might  be  different,  and  some  might  be  omitted  as  un- 
important ;  thus,  for  instance,  the  mud-drum,  which  is  of  im-J 
portance  in  a  boiler  for  power,  because  it  is  receiving  constant 
accessions  of  water  with  more  or  less  impurities,  is  seldom 
on  heating  boilers  when  they  are  supplied  with  water  of 
condensation.  The  importance  of  provisions  for  cleaning  is; 
less  in  heating  than  in  power  boilers,  but  should  not  bJ 
neglected. 

77.  General  Types  of  Boilers. — Power-boilers. — It  seems 
necessary  to  consider  boilers  built  for  high-pressure  steam  andj 
of  large  sizes  as  a  separate  class  from  those  used  principally  ini 
heating  small  buildings,  although  boilers  of  similar  structure^ 
may  be  constructed  for  heating.  These  boilers  will  be  spoken 
of  as  power-boilers,  and  are  required  t^  fulfil  conditions  as  tol 
strength  and  capacity  not  needed  in  heating-boilers. 

The  principal  boilers  of  this  type  now  in  use  can  be  grouped 
into  two  classes,  viz.,  fire>tube  and  water-tube  boilers,  and  onej 
or  the  other  of  this  type  must  be  used  for  heating  purposes, 
with  the  present  condition  of    the    market,   whenever  high- 
pressure  steam  is  required. 

The  fire-tube  or  common  tubular  boiler  consists  of  a  cylin-« 
drical  boiler  with  plain  heads,  connected  by  a  large  number  of 


S  TEA  M-HEA  TING  B  OILERS.  —HO  T-  &A  TER  HE  A  TERS.      1 29 

tubes  which  serve  as  passages  for  the  smoke  or  heated  gases. 
The  fire  is  built  underneath,  and  the  smoke  passes  horizontally 
either  twice  or  thrice  the  length  of  the  boiler.  The  general 
form  of  this  boiler  is  shown  in  Fig.  1 14.  This  boiler  is  also 


FIG.  114. — HORIZONTAL  TUBULAR  BOILER. 

used  sometimes  in  a  vertical  position  with  the  fire  beneath  one 
head,  in  which  case  it  is  called  a  vertical  tubular.  The  water- 
tube  boilers  have  the  water  in  small  tubes,  and  the  heated 
gases  pass  out  between  the  tubes.  In  this  class  of  boilers 
the  steam  is  contained  in  drums  or  horizontal  cylinders,  which 
are  located  above  the  heating  surface.  The  tubular  boilers 
are  made  in  small  sizes,  10  horse-power  and  larger,  while 
the  water-tube  boiler  for  power  is  seldom  less  than  60  horse- 
' power  capacity. 

Heating-boilers. — The  boilers  which  are  used  for  steam-heat- 
ing are  designed  in  a  multiplicity  of  forms,  and  present  examples 
of  nearly  every  possible  method  of  producing  extejid^d-aujiaces, 
both  of  the  water-tube  and  fire-tube  types.  They  are  generally 
built  for  low-pressure  steam,  and  are  expected  to  be  used 
,'mainly  in  buildings  where  the  condensed  water  is  returned  by 
gravity  to  the  boiler  without  pumps  or  traps.  They  are  usu- 
ally built  in  small  sizes  having  a  capacity  of  250  to  2000  ft.  of 
radiating  surface  (2^  to  20  H.P.),  and  are  fitted  with  safety- 
valves,  water  and  steam  gauges  and  damper  regulators. 

The  limits  of  this  book  prevent  a  detailed  description  of 
any  make  of  heating-boiler,  but,  the  leading  general  types  are 
described.  Several  types  of  the  power-boiler  are  described 
quite  in  detail,  and  much  that  is  said  with  respect  to  them  will 
ipply  in  a  general  way  to  heating-boilers. 


130 


HEATING   AND    VENTILATING   BUILDINGS. 


The  following  classification  of  steam-heating  boilers  was 
suggested  by  one  presented  by  Mr.  A.  C.  Walworth  in  a  paper 
before  the  New  York  Convention  of  Master  Steam  and  Hot* 
water  Fitters,  June,  1894: 


CLASSIFICATION   OF   HEATING-BOILERS. 

Plain      (SPherical      ,Ver, 
Surface    j  Cylindrical  \  3£££# 

.  •      (  Wrought  Iron,  Projecting  Tubes 


Boiler 


Surface 


jrreguiar  surface 


Divided 
Surface 


r 


Fire-tube 


Vertical 

Horizontal 

Locomotive 


Tubular 


f  Straight  tubes 
|  Curved      " 
Water-tube   -{  Spiral 

'  |  Coil  of       " 
LDrop 


Sectional  •< 


Horizontal 


Packed  joints 
Screwed     " 
Faced 

Packed  joints 
Screwed     " 
Faced 


78.  The    Horizontal    Tubular    Boiler. — This  boiler 
manufactured  in  many  places,  so  that  in  many  respects  it  is 
standard  article  of  commerce,  and  it  can  be  purchased  in  neai 
every  market  for  a  slight  advance  over  the  cost  of  materials  ai 
labor  used  in  its  construction.    In  the  construction  of  this  boil< 
the  shell  is  now  almost  invariably  made  of  soft  steel  of  a  thi< 
ness  depending  upon  the  pressure  which  the  boiler  is  expect( 
to  sustain.     The  heads  of  the  boiler  are  made  of  flange  st( 
and  are  generally  -fa  inch  thicker  than  the  material  in  the  sh< 
Lap-welded  iron  tubes  are  almost  invariably  used,  the  stand; 
sizes  being  as  given  in  Table  XVII.     The  tubes  are  expandi 
into  the  heads  of  the  boiler  and  may  or  may  not  be  beaded,  ai 
are  generally  arranged  in  parallel  vertical  rows  in  the  lower 
thirds  part  of  the  boiler.     In  some  instances  the  middle  row 
tubes  is  omitted  with  good  results.     It  is  not  a  good  plan 
stagger  the  tubes,  since  in  that  case  they  are  difficult  to  cl( 


S  TEA  M-HEA  TING  B  OILERS. —HO  T-  WA  TER  HE  A  TERS.      \  3 1 


and  also  act  to  impede  the  circulation  of  the  water.  The  boiler 
should  be  provided  with  manholes,  with  strongly  reinforced 
edges,  so  that  a  person  can  enter  for  cleaning.  The  heads  of 
the  boiler  above  the  tubes  should  be  thoroughly  braced  in 
order  to  sustain  safely  any  pressure  from  the  inside  of  the 
boiler. 

Domes  are  often  placed  above  the  horizontal  part  of  the 
boiler,  and  serve  to  increase  the  capacity  for  the  storage  of 
steam  and  also  provide  ready  means  of  drawing  off  dry  steam. 
The  dome  is  always  an  element  of  weakness,  and  if  used  it 
should  be  staved  and  reinforced  in  the  strongest  possible  man- 
ner. The  dome  is  frequently  omitted,  and  steam  taken  directly 
from  the  top  of  the  shell  or  djrawn  through  a  long  pipe  with 
numerous  perforations,  termed  a  petticoat  pipe. 

In  construction  this  boiler  must  be  strongly  braced  wher- 
ever any  flat  surfaces  are  exposed  to  pressure,  and  the  girth 
and  longitudinal  seams  must  be  riveted  in  such  a  manner  as  to 
secure  the  maximum  strength. 

The  following  table  gives  principal  dimensions  for  a  series 
of  horizontal  tubular  boilers  designed  for  a  working  pressure 
of  So  to  100  pounds  per  square  inch : 


8000 

i 

16 

60 

80 

Diameter  of  boiler  inches 

36 

3fi 

48 

60 

66 

Length  of  boiler,  feet  

1/4 

J! 

8 

10 

10 

12 

9/32 

12 

9/32 

12 

sA6 

14 

s/ifi 

16 

16 

3/8 

Thickness  of  shell,  inches  

Thickness  of  heads,  inches  

5/16 

S/i6 

5/16 

V8 

3/8 

3/8 

3/8 

V8 

"1/8 

1/2 

1/2 

Length  of  flues,  feet  

6 

8 

10 

10 

12 

12 

16 

16 

Number  of  flues  

S2 

32 

3° 

32 

40 

40 

52 

70 

70 

83 

104 

Diameter  oi  flues,  inches  

2* 

fk 

3 

3 

3 

3 

3 

3 

Square  feet  of  heating:  surface. 
Proper  diam.  of  smoke-pipe  (20' 

155 

192 

239 

310 

385 

462 

60^ 

765 

901 

1206 

1504 

chimney),  inches  

M 

14 

15 

17 

18 

2O 

24 

26 

7l8 

32 

37 

Approximate  weight,  Ibs  
V*  t.  of  grate  and  fixtures,  Ibs  

1800 

1200 

2000 
I4OO 

2700  3100 
1600  1800 

4000 

2100 

4600 
2200 

5600 
2800 

7000 
5200 

8000 
54oo 

10500 
7200 

12500 
7500 

Fifteen  square  feet  of  surface  to  each  horse-power. 

79.  Locomotive  and  Marine  Boilers.  —  Boilers  of  the 
horizontal  tubular  type  with  a  fire-box  entirely  enclosed  and 
surrounded  by  heating  surface  are  usually  termed  locomotive 
.boilers  from  the  fact  that  such  construction  is  common  on 
locomotives.  Boilers  of  this  style  are  sometimes  used  for  sta- 


132 


HE 'A  7 'ING   AND    VENTILATING   BUILDINGS. 


tionary  power  purposes,  and  possess  the  advantage  over  the 
plain  tubular  boiler  of  requiring  no  brick  setting.  They  are 
not,  however,  as  strong  in  form  as  the  plain  tubular,  since  large 
flat  surfaces  have  to  be  used  over  the  fire-box. 

Marine  Boilers. — A  cylindrical  boiler  with  an  internal  cylin- 
drical fire-box  is  principally  used  on  large  boats.     The  fire-box 


FIG.  115. — LOCOMOTIVE  BOILER. 

is  often  corrugated.  This  form  of  boiler  is  very  strong  and 
efficient,  but  because  of  cost  of  con- 
struction has  been  little  used  for  station- 
ary  purposes. 

79.  Vertical  Boilers.— Vertical  boil- 
ers of  large  size  are  made  in  every 
respect  like  the  horizontal  tubular  boiler, 
but  are  set  so  that  the  flame  plays  di- 
rectly on  one  head  and  the  heated  gases 
pass  up  through  tubes.  These  boilers 
are  generally  provided  with  a  water-kg 
which  extends  below  the  lower  crown 
sheet  and  is  intended  to  receive  deposits 
of  mud,  etc.,  from  the  boiler.  They  are 
usually  made  so  that  the  heat  passes 
directly  out  of  the  top  of  the  flue,  but 
in  some  cases  the  heat  is  made  to  pass 

»down  a  portion  of  the  length  of  the  ex- 
FIG.  116. — UPRIGHT  TUBU-  .          i       i     n     i_   r  i.    •          j-     i 

LAR  BOILER.  ternal    shell    before    being    discharged. 

They  are  economical  in  the  use  of  fuel 
and  occupy  very  small  amount    of   floor-space  ;  they  require, 


S  TEA  M-hEA  TING  ROILERS.  —HO  T-  WA  TER  HE  A  TERS.     133 

however,  a  great  deal  of  head-room,  are  very  easily  choked  up 
with  deposits  and  sediment,  very  difficult  to  clean,  and  very 
likely  to  leak  around  the  tubes  in  the  lower  crown-sheet,  and 
consequently  have  a  short  life. 

Vertical  boilers  with  horizontal  radial  tubes  projecting 
outward  with  ends  closed,  known  as  porcupine  boilers,  are 
also  on  the  market,  and  quite  recently  a  vertical  boiler  of  the 
water-tube  type  has  been  constructed. 

80.  Water-tube  Boilers. — The  water-tube  boilers,  which 
are  used  for  power  purposes,  are  designed  to  withstand  great 
pressures,  and  can  be  purchased  in  sizes  ranging  from  60  to  500 
horse-power  per  boiler.  The  general  construction  of  these 
boilers  is  such  as  to  have 
the  water  on  the  inside  of 
the  tubes  and  the  fire  with- 
out. There  are  two  gen- 
eral forms  :  first,  those  with 
straight  tubes,  and  second, 
those  with  curved  tubes. 

In  all    cases   they  have 

large    steam-drums   at    the 

1-1  ,  .       FIG.  117. — BABCOCK  &  WILCOX  BOILER. 

top,  which  are  connected  to 

the  heating-surface  by  headers  filled  with  water.  In  the  Bab- 
cock  &  Wilcox,  Heine,  and  Root  the  tubes  are  inclined  and 
parallel,  and  are  connected  at  the  end  with  headers,  the  fire 
being  applied  in  each  case  under  the  elevated  portion  of  the 
inclined  tube,  so  as  to  insure  circulation  uniformly  in  one 
direction. 

In  the  Babcock  &  Wilcox  boiler,  cast-iron  zigzag  headers 
are  used  ;  in  the  Root  boiler,  the  tubes  are  connected  together 
by  external  U-shaped  bends;  in  the  Heine  boiler  (Fig.  120), 
the  tubes  are  connected  to  large,  flat-stayed  surfaces.  In  the 
Babcock  &  Wilcox  and  Heine  boilers,  feed-water  is  supplied  at 
the  lower  part  of  the  top  drums  ;  while,  in  the  Root  boiler,  it  is 
supplied  to  a  special  drum  in  the  down-circulation  tubes  at 
the  back  end  of  the  boiler.  The  Stirling  boiler  has  three  hori- 
zontal drums  at  the  top  connected  by  curved  tubes  to  a 
single  lower  drum  at  the  back  end  of  the  boiler ;  the  Hogan 
has  one  drum  at  top  and  two  at  bottom,  which  are  parallel  and 


134  HEATING   AND    VENTILATING  BUILDINGS. 

connected  by  curved  tubes,  and  also  a  series  of  down-circu- 
lating tubes  connecting  the  same  drums,  but  not  exposed  to  the 
heat  of  the  fire.  In  the  Stirling  boiler,  the  feed-water  is  intro- 


FIG.  118. — ROOT  BOILER. 


duced  in  the  top  drums ;  in  the  Hogan  boiler,  into  a  special 
heater  and  purifier  arranged  as  a  part  of  the  downward  circu- 
lation. 


FIG.  119. — STIRLING  BOILER. 

The  Harrison  boiler  consists  of  an  aggregation  of  spheres 
of  cast  iron  or  steel  connected  by  necks,  forming  what  is  to  be 
considered  rather  as  a  sectional,  than  a  water-tube  boiler.  These 


S  TEA  M-HEA  TING  BOILERS.— HO  T-  WA  TER  HE  A  TERS.      1 3  5 


spheres  are  held  in  place  by  bolts,  which  will  stretch  and  act 
as  safety-valves  in  case  of  excessive  pressure. 

In  addition  to  the  water-tube  boilers  for  power  purposes 
which  have  been  mentioned  here,  there  are  many  others  which 
cannot  be  described  in  the  space  at  our  command,  but  of 
which  we  may  name  the  National,  Campbell  &  Zell,  and 
the  Caldwell  as  worthy  of  notice. 

All  the  water-tube  boilers  are  provided  with  mud-drums, 
which  are  usually  cast-iron  cylinders  removed  from  the  circu- 


FIG.  120. — HEINE  BOILER. 

lation  and  intended  to  receive  any  deposits  of  scale  or  material 
which  is  loosened  in  the  process  of  circulation. 

8l.  Hot-water  Heaters.— Hot-water  heaters  differ  essen- 
tially from  steam-boilers,  principally  in  the  omission  of  a  reservoir 
or  space  for  steam  above  the  heating 
surface.  The  steam-boiler  might  an- 
swer as  a  heater  for  hot  water,  but 
the  large  capacity  left  for  the  steam 
would  tend  to  make  its  operation 
slow  and  quite  unsatisfactory. 

The  passages  in  a  hot-water  heater 
need    not    extend    so    directly   from 
bottom  to  top  as  in  a  steam-heater, 
since  the  problem  of  providing  for 
the  early  liberation    of    the    steam- 
bubbles    does    not    have  to  be   con- 
sidered.    In  general,  the  heat   from 
the  furnace  should  strike  the  surfaces  FIG.  121.— VERTICAL  MAGAZINE 
in  such  a  manner  as  to  increase  the          HOT-WATER  HEATER. 
natural  circulation,  and  not  act  to  produce  a  backward  circula- 
tion.    This  may  be  accomplished  in  a  certain  measure  'by  ar- 


136  HEATING   AND    VENTILATING   BUILDINGS. 

ranging  the  heating-surface  so  that  a  large  proportion  of  the 
direct  heat  will  be  absorbed  near  the  top  of  the  heater. 

There  is  a  great  difference  of  opinion  as  to  the  relative 
merits  of  horizontal  and  vertical  heating-surfaces  for  this  pur- 
pose, but  the  writer  cannot  find  that  any  experiments  have  been 
made  which  satisfactorily  decide  this  question.  Where  the  sur- 
face is  very  much  divided,  and  the  fire  is  maintained  at  a  high 
temperature,  considerable  steam  is  likely  to  be  formed,  and  this 
always  acts  in  a  certain  measure  to  increase  circulation  in  the 
heating-pipes  and  diminish  it  in  the  heater  ;  it  is  likely  also  to 
produce  a  disagreeable  crackling  noise. 

Practically,  the  boilers  for  low-pressure  steam  and  for  hot 
water  differ  from  each  other  very  little  as  to  the  character  of 
the  heating-surface,  and  in  describing  the  general  classes  which 
are  in  use  no  attempt  will  be  made  to  make  any  distinction  as 
to  whether  the  apparatus  will  be  used  for  hot-water  or  steam 
heating.  If  designed  for  steam-heating,  a  reservoir  or  chamber 
connected  with  the  circulating  system  is  in  every  case  pro- 
vided, containing  water  in  its  lower  part  and  considerable 
steam  capacity  above  the  water-line,  also  sufficient  area  of 
water-surface  to  permit  the  separation  of  the  steam  from  the 
water  without  noise  and  violent  ebullition. 

82.  Classes  of  Heating-boilers  and  Hot-water  Heaters 

— Plain-surface  Boilers. — There  are  probably  no  boilers  or 
heaters  built  at  the  present  time  with  a  plain  surface,  either 
spherical  or  cylindrical,  since  the  expense  of  a  given  amount  of 
surface  in  that  form  would  practically  preclude  its  use. 

Extended-surface  Heaters  (Figs.  122  and  123). — Heaters  of 
class  with  extended  and  irregular  surface,  are  used  quite 
extensively  in  hot-water  heating,  and  with  the  addition  of 
domes  are  used  to  some  extent  in  steam-heating.  In  these 
heaters  the  water  is  received  at  the  lowest  point,  as  at  A,  and 
is  heated  as  it  gradually  rises,  receiving  the  effect  of  the  fire 
at  various  projections,  and  is  finally  discharged  at  B.  The 
grate  is  at  G,  the  smoke  being  discharged  at  5.  The  smoke 
and  heated  gases  move  in  nearly  a  direct  line  in  Fig.  122,  and 
in  a  sinuous  course  in  Fig.  123. 

A  form  which  is  in  extensive  use,  and  in  which  water 
and  smoke  are  each  grouped  in  one  body,  is  shown  in 


STEAM-HE  A  TING  BOILERS.— HO  T-  WA  TER  HE  A  TERS.      I  37 

Fig.  124.  In  this  case  the  extended  surface  is  produced  by  the 
wedge-shaped  hollow  prisms  extending  over  the  fire-space. 
The  heated  gases  have  a  return  circulation  around  the  lower 
portion  of  the  heater,  and  also  come  in  contact  with  a  top 
dome  from  which  the  heated  water  is  drawn  off. 


FIG.  122. — EXTENDED-SURFACE  FIG.  123. — EXTENDED-SURFACE 

HEATER.  HEATER. 


FTG.    124. — EXTENDED  SURFACE, 
VERTICAL  PRISMS. 


FIG.   125.  —  RADIAL  AND  CURVED 
WITH  EXTENDED  SURFACE. 


Heaters  belonging  to  the  extended-surface  class  made  with 
vertical  cylinders,  into  which  are  connected  either  straight  hori- 
zontal tubes  with  closed  end,  as  shown  on  the  right-hand  side 
of  Fig.  125,  or  U-sHaped  projections  of  pipe  either  horizontal 
or  slightly  inclined,  are  in  use  for  both  water-  and  steam-heat- 


138 


HEATING  AND    VENTILATING   BUILDINGS. 


ing.  In  case  they  are  used  for  steam-heating  the  water-line  is 
carried  at  sufficient  distance  from  the  top  of  the  cylinder  to 
give  the  required  steam-space,  and  the  heater  is  supplied  with 
both  pressure-  and  water-gauges.  The  heated  gases  pass 
around  the  cylindrical  part  of  the  boiler  and  may  be  made 
to  circulate  among  the  projections  by  means  of  baffle-plates. 

Tubular  Boilers. — Heating-boilers  with  fire-tubes  and  with 
a  steel  shell  similar  in  construction  to  the  horizontal  and 
vertical  tubular  boiler  described  in  Articles  76  and  78,  are  in 
use  for  heating  to  considerable  extent  in  the  forms  already  de- 
scribed. Modifications  of  these,  with  return  flues  arranged 
so  that  the  heat  passes  both  upward  and  downward,  and  also 
with  two  or  more  short  cylindrical  shells  connected  together 
by  tubes  filled  with  water,  are  in  extensive  use.  Very  few  hori- 
zontal tubular  boilers,  or  boilers  of  the  locomotive  type,  are 
used  for  the  heating  of  small  buildings. 

Water-tube  Boilers. — Water-tube  boilers  of  all  classes  and 
various  modifications  are  in  extensive  use  for  heating.  The 
tubes  are  made  of  either  cast-iron  or  wrought-iron  pipe.  The 
pipe-boilers  which  are  in  the  market  are  arranged  with  nearly 


FIG.  126.— FIELD  TUBE. 

every  form  of  heating-surface;  some  are  built  with  heating- 
surface  in  the  form  of  the  pipe-coil,  as  shown  in  Fig.  92,  page 
108,  and  others  in  the  form  of  a  manifold  coil,  as  shown  in  Fig. 
93,  page  108.  Still  other  boilers  have  the  pipe  arranged  in  the 
form  of  a  spiral  connecting  with  a  receiving-drum  below  and  a 
steam-drum  above.  The  heated  gases  are  arranged  to  move 


S  TEA  M-HEA  TING  BOILERS.  —HO  T-  WA  TER  HE  A  TERS.      1 39 


in  some  cases  parallel  with  the  surfaces,  and  in  other  cases  at 
right  angles. 

The  Field  tube  is  used  extensively  for  the  purpose  of  in- 
creasing the  heating-surface;  in  its  original  form  it  consisted 
of  a  tube  with  a  closed  end  projecting  downward  and  expanded 
into  the  boiler-shell ;  into  this  extended  another  tube  which  did 
not  reach  quite  to  the  bottom,  and  was  held  in  position  by 
an  internal  perforated  support,  as  shown  in  Fig.  126.  This  is 
used  in  heating-boilers  with  various  modifications  both  pro- 
jecting downward  and  horizontally.  When  used  projecting 
downward,  it  is  termed  a  drop-tube,  and  is  supplied  either  with 
an  internal  tube,  as  shown,  or  a  partition  ;  when  used  hori- 
zontally the  internal  tube  is  frequently  supplied  from  a  com- 
partment separated  from  that  to  which  the  external  tube  is 
attached.  Fig.  127  illustrates  a  type  of  heating-boiler  which 
is  quite  extensively  used  for  both  hot  water  and  steam,  and  is 
built  by  different  manufacturers,  either  of  steel  or  cast  iron. 
The  heater  consists  of  a  cylindrical  drum,  the  lower  surface  of 

A& 

B     B 

IHkH 


I          |     .   .  .  i"i  i"      r^ 

L    fdi    «4   fei   fei    J=S    P— -    F=    f=   F 


DROfJTUBE 


FIG.  127.— DROP-TUBE  SURFACE.     FIG.  128. — DROP-TUBE  AND  COIL-HEATER. 

which  is  covered  with  tubes  of  the  type  described  which  pro- 
ject downward.  The  tubes  directly  over  the  fire  and  over  the 
fire  door  are  short,  while  those  around  the  fire  are  sufficiently 
long  to  form  the  external  walls  of  the  heater.  The  return 
water  is  received  in  one  of  the  long  pipes  near  the  bottom  of 
the  heater,  and  the  steam  or  heated  water  is  taken  off  at  the 
top.  The  drum  in  one  of  these  heaters  is  provided  with  a 
baffle-plate  connected  to  the  diaphragm  in  the  drop-tube,  so 


140 


HEATING   AND    VENTILATING   BUILDINGS. 


that  the  circulation  must  take  place  in  a  vertical  direction  in 
the  tube. 

Fig.  128  shows  a  heater  in  which  the  surface  is  made  up 
partly  of  pipe-coils  and  partly  of  drop-tubes.  The  return 
water  is  received  in  the  lower  concentric  drum,  and  as  it 
is  warmed  passes  to  the  top  drum  of  the  heater,  from  which  it 
flows  to  the  building;  a  type  of  heater  in  many  respects 
similar  is  made  without  drop-tubes,  the  whole  surface  being 
obtained  by  use  of  pipe-coils,  made  either  with  return  bends 
or  with  branch  tees. 

Sectional  Boilers. — The  greater  number  of  cast-iron  boilers 
are  made  by  joining  either  horizontal  or  vertical  sections. 
These  sections  are  joined  in  some  instances  by  a  screwed 
nipple,  in  other  cases  by  a  packed  or  faced  joint,  and  are  held 
in  place  with  bolts.  The  sections  generally  contain  water  and 


O*      O    O 


00 
Oo 

1    Oo 
Co 

FIG.  130. 
BOILER  WITH  HORIZONTAL  SECTIONS. 


PLAN  OF  SECTION 

FIG.  129. 

BOILER  WITH  HORIZONTAL 
SECTIONS. 

steam,  and  the  heated  gases  circulate  around  the  sections  in 
flues  provided  for  that  purpose.  The  joints  in  the  flues  are 
usually  made  tight  enough  to  prevent  the  escape  of  smoke  by 
the  use  of  an  asbestos  or  similar  cement. 


STEAM-HEATING  BOILERS.— HOT-WATER  HEATERS.     14* 


Horizontal  Sections. — Fig.  129  represents  a  type  of  heater  in 
which  the  various  sections  are  horizontal,  the  surface  being  in- 
creased to  any  amount  by  adding  sections.  This  form  is  used 
extensively  in  a  number  of  hot-water  heaters.  Fig.  130  shows 
another  form  of  boiler  made  in  a  similar  manner,  but  with  the 
sections  of  such  form  as  to  produce  both  an  up  and  down 
circulation  within  the  heater.  The  up  circulation  takes  place 
over  the  hottest  portion  of  the  fire,  the  down  circulation  in 
special  external  passages  which  are  not  heated. 

Vertical  Sections. — Boilers  with  vertical  sections  are  made  in 
the  same  manner  in  many  respects,  the 
sections  being  united  by  internal  or  ex- 
ternal connections.  When  united  by  ex- 
ternal connections,  screwed  nipples  con- 
necting the  sections  to  outside  drums,  of 
the  general  form  as  shown  in  Fig.  131, 
are  usually  employed.  In  this  case  the 
return-water  is  received  into  horizon- 
tal drums  AA,  which  extend  the  full 
length  of  the  heater,  and  flows  into  the 
lower  part  of  each  section.  The  steam 
or  hot  water  is  drawn  off  from  a  similar 
drum,  B,  which  extends  over  the  top  of 
the  heater  and  is  connected  with  each 
section  by  a  screwed  nipple.  Fig.  130 
shows  methods  of  attaching  steam-  and 

water  gauges.     This  form  is  used  quite  extensively  in  steam- 
heating  and  to  some  extent  for  hot-water  heating. 

83.  Heating-boilers  with  Magazines. — Nearly  all  of  the 
heating-boilers  are  manufactured  as  required  with  or  without  a 
magazine  to  hold  a  supply  of  coal.  The  magazine  in  most 
cases  consists  of  a  cylindrical  tube  opening  at  or  near  the  top 
of  the  heater  and  ending  eight  to  twelve  inches  above  the 
grate.  The  magazine  is  filled  with  coal,  which  descends  as  com- 
bustion takes  place  at  the  lower  end,  and  provides  fuel  for 
further  combustion  (see  Fig.  121).  The  magazine  works  suc- 
cessfully with  anthracite  coal,  which  is  that  ordinarily  employed 
in  domestic  heating,  but  it  takes  up  useful  space  in  the  heater, 
decreases  the  effective  heating  surface  for  a  given  size,  and  in 


142  HEATING   AND    VENTILATING   BUILDINGS. 

that  respect  is  objectionable.  The  writer's  own  experience 
would  lead  him  to  believe  that  the  magazine  heater,  except  in 
very  small  sizes,  requires  as  much  attention  as  the  surface 
burner,  and  consequently  has  no  special  advantage.* 

84.  Heating-boilers  for  Soft  Coal. — It  is  quite  probable 
that  no  furnace,  either  for  power  or  heating  boilers,  has  yet 
been  produced  which  will  consume  soft  coal  without  more  or 
less  black  smoke.     This  smoke  is  due  principally  to  the  imper- 
fect combustion  of  the  hydrocarbons  contained  in  the  coal.    The! 
hydrogen  burning  out  after  the  gases  have  left  the  fire  leaves 
solid  carbon  in  the  form  of  small  particles,  which  float  with  and 
discolor  the  products  of  combustion.     The  amount  of  loss  as 
found  by  experiment  in  Sibley  College,f  even  when  dense  black 
smoke  is  produced,  seldom  reaches  one  per  cent,  and  is  of  noi 
economical   importance.     The  sooty  matter  produced  in  the| 
combustion  of  this  coal  is  likely  to  adhere  to  the  water-heatingl 
surfaces,  and  if  these  are  minutely  divided  it  will  be  certain  to3 
choke  the    passages    for   the  gases   of   combustion.     For  the  = 
combustion   of   soft   coal  those  heaters  have  been    the    most 
successful  which  have  a  grate  with  small  openings,  and  with  an  = 
area  50  to  70  per  cent  as  large  as  that  needed  for  anthracite 
coal,  also  with  the  heating-surface  of  comparatively  simple  form! 
and  arranged  so  as  to  be  easily  cleaned.     It  is  considered  im- 
portant that  the  air-flues  be  so  arranged  as  to  keep  the  products 
of  combustion  as  hot  as  possible.     This  coal  is  likely  to  swell 
when  first  heated,  and  cannot  be  fed  successfully  by  a  maga- 
zine. 

*  Magazine  heaters  have  been  constructed  with  a  magazine  set  obliquely 
above  and  to  the  side  of  the  grate,  and  in  that  position  are  not  open  to  all  the 
objections  stated. 

f  See  Table  XII,  page  390. 


CHAPTER  VIII. 


SETTINGS   AND  APPLIANCES  -METHODS  OF   OPERATING 
BOILERS  AND  HEATERS. 

85.  Brick  Settings  for  Boilers.  —  Horizontal  tubular  boilers 
and  a  few  heating-boilers  require  to  be  set  in  brickwork,  of 
which  the  general  arrangement  is  shown  in  Fig.  132.  The 
horizontal  tubular  boiler  is  usually  supported  from  cast-iron 
flanges  which  are  riveted  to  the  sides  of  the  shell,  and  which  rest 


,.., FIG.   132. — PERSPECTIVE  VIEW  OF  TUBULAR  BOILER  st/i   IN   BRICKWORK. 

directly  on  the  walls  of  brickwork,  or  are  supported  b)-  sus- 
>pension-rods  from  above.  In  some  instances  the  boiler-lugs 
'rest  on  cast-iron  columns  embedded  within  the  brickwork,  and 
of  such  a  length  that  all  the  brickwork  above  the  grates  can 
be  removed  without  affecting  the  setting.  In  setting  the  boiler 

143 


144 


HEATING   AND    VENTILATING   BUILDINGS. 


the  back  end  should  be  slightly  lower  than  the  front,  in  ord< 
that  the  entire  bottom  of  the  boiler  may  be  drained  at  the  blow- 
off  pipe.     One  of  the  lugs  of  the  boiler  on  each  side  should 
anchored  in  the  brickwork ;  the  others  should  rest  on  rollei 
which  in  turn   rest   on   an  iron   plate  embedded   in  the  bricl 


*TS^w 

k 


walls.     This  permits  expansion  due  to  heating  and  cooling 
take  place  without  straining  the  boiler.     If  the  boiler  is  'n< 
over  14  feet  in  length,  two  lugs  on  a  side  will  be  sufficient 
sustain  it,  but  if  it  is  of  greater  length,  more  lugs  will  need 


SETTINGS  AND  APPLIANCES. 


145 


be  supplied.  The  brickwork  surrounding  the  boiler  is  more 
durable  if  built  with  an  air-space,  as  shown  in  Fig.  134.  It 
must  be  thoroughly  stayed,  by  means  of  cast-iron  braces,  con- 
nected with  tie-rods  at  top  and  bottom  of  wrought  iron  to 


FIG.  134. — SECTIONAL  VIEW  OF  BOILER- SETTING. 

prevent  transverse  or  longitudinal  motion.  The  top  may  be 
I  arched  over  so  as  to  leave  a  passage  for  the  hot  gases  directly 
»ver  the  shell,  as  in  Fig.  132,  or  made  to  rest  directly  on  the 
.  boiler,  and  the  hot  gases  taken  away  at  the  front  end  by 
j!  means  of  a  flue,  usually  termed  a  breeching,  which  extends  to 
the  chimney.  The  practice  of  taking  the  heated  gases  from 
Hhe  front  end  of  the  boiler  is  rather  more  common  than  that  of 
Returning  them  to  the  back  end  over  the  top,  and  there  are 
I  many  engineers  who  believe  that  the  hot  gases  injure  the  boiler 
||when  coming  in  contact  with  the  shell  above  the  water-line. 
I  Fig5-  133, 134,  and  135  show  longitudinal  and  transverse  sections 
p)f  a  boiler-setting,  with  smoke-pipe  or  breeching  in  front,  which 
lean  be  highly  commended  as  representing  the  best  practice. 

The  depth  of  foundation  to  be  used  in  boiler-setting  will 
depend  upon  the  character  of  the  soil  and  the  weight  of  the 
pboiler.     For  large  tubular  and  water-tube  boilers  it  should  gen- 
erally be  not  less  than  3  feet.     Fire-brick  of  the  best  quality 


146 


HEATING  AND    VENTILATING  BUILDINGS. 


should  be  used  to  line  the  brick  walls  for  a  height  equal  to  that 
from  the  grate  to  the  water-line  of  the  boiler,  and  these  should 
be  arranged  so  that  if  necessary  they  can  be  relaid  without 
disturbing  the  outer  brickwork.  In  the  setting  shown  in  Figs. 
133-134  the  top  of  the  boiler  is  covered  with  a  coating  of  some 


good,  non-conducting  material,  for  which  magnesia,  asbestos 
or  mineral  wool  may  be  recommended,  put  on  while  in  a 
plastic  condition  to  the  depth  of  2  inches  with  a  mason' 


SETTINGS  AND   APPLIANCES. 


FIG.  136. 
BRICK-SET  MAGAZINE  BOILER. 


trowel.     Brickwork  is  often  used  ;  but  it  is  heavier,  and  quite 
liable  to  crack  from  the  effects  of  heat. 

86.  Setting  of  Heating-boilers. — If  heating-boilers  are  to 
be  set  in  brickwork,  the  special  directions  which  have  already 
been  given  can  be  applied,  with 
such  modifications  as  may  be 
needed  for  the  boiler  in  ques- 
tion. Nearly  all  heating-boilers 
are  now  set  in  what  is  called  a 
portable  setting,  in  which  no 
brick  whatever  is  used.  Some 
of  the  heaters  are  made  by  the 
system  of  manufacture  adopted 
so  that  no  outside  casing  is  re- 
quired, as  in  Fig.  138;  others 
require  a  thin  casing  of  galvan- 
ized or  black  iron  which  is  lined 
with  some  non-conducting  ma- 
terial, as  magnesia,  asbestos  fibre,  or  rock  wool,  which  is  placed 
outside  the  heater  and  arranged  so  as  to  enclose  a  dead-air 
space,  as  in  Fig.  137.  These  coverings  are  nearly  as  efficient 
|jn  preventing  the  loss  of  heat  as  brickwork,  and  they  form  a 
more  cleanly  and  neater  appearing  job. 

The   slight   amount    of  heat   which    escapes   from   such  a 
setting  is   seldom  more   than  that  required  to  warm  up  the 
jlbasement  or  room  in  which  the  heater  is  located. 

The  boiler  must  in  all  cases  be  provided  with  a  steam- 
i;gauge,  safety-gauge,  and  damper  regulator,  all  of  which  are 
\  specially  described  later.  The  steam-gauge  should  be  either 
Connected  below  the  water-level  or  else  provided  with  a  siphon 
jlto  prevent  dry  steam  entering  the  interior  tube.  A  safety- 
-valve of  the  single-weighted  type  is  preferable  and  should 
be  connected  at  the  top  of  the  heater.  The  damper  regu- 
i  lator  usually  consists  of  a  rubber  diaphragm  which  is  acted 
pon  by  pressure  so  as  to  open  and  close  the  dampers  as  required. 
|:  It  will  prove  more  durable,  generally,  if  connected  below  the 
|%ater-line  and  located  about  on  a  level  with  the  top  of  the 
I  heater,  as  this  will  insure  the  contact  of  water  against  the  rubber 
diaphragm.  Fig.  137  represents  a  boiler  with  portable  setting 


148 


HEATING  AND    VENTILATING  BUILDINGS. 


with  external  iron  casing  and  equipped  with  all  appliances,  and 
Fig.  138  represents  a  portable  setting  without  enclosing  case. 

Hot-water  heaters  are  set  in  the  same  general  manner  as 
steam-boilers.  Each  should  be  provided  with  thermometers 
showing  both  the  temperature  of  the  flow  and  the  return  water, 


FIG. 


137. — HEATING-BOILER  WITH 
PORTABLE  SETTING. 


FIG. 


138.— HEATING-BOILER    WITH; 
PORTABLE  SETTING. 


and  with  a  pressure-gauge  graduated  to  show  pressure  of  water 
in  feet  and  sufficiently  large  to  show  any  variation  in  height  in 
the  open  expansion  tank.  The  dampers  to  a  hot-water  heater 


FIG.   139. — SECTION  OF  LEVER  VALVE,  OLD  FORM. 

cannot  be  opened  and  closed  by  variation  in  pressure,  but 
reliable  thermostats  are  now  on  the  market  which  will  operate 
the  dampers  by  change  of  temperature  in  the  various  rooms 
of  the  building. 


SETTINGS  AND   APPLIANCES. 


149 


87.  The  Safety-valve. — The  safety-valve  has  been  used 
since  the  earliest  days  of  boiler  construction  for  reducing  the 
pressure  when  it  reached  or  exceeded  a  certain  limit.  It 
has  been  built  in  various  forms,  but  in  every  case  has  con- 
sisted essentially  of  a  valve  opening  outward  and  held  in 
place  by  a  weight  or  a  spring.  One  form  in  common  use  con- 
sists of  a  valve  held  in  place  by  a  weight  on  the  end  of  a  lever, 
shown  in  Fig.  139  in  section  and  in  Fig.  140  in  elevation.  In 
this  form  of  safety-valve  the  force  required  to  lift  the  valve 


FIG.  140.— LEVER  SAFETY- VALVE,  MODERN  FORM. 

can  be  regulated  by  sliding  the  weight  to  different  positions 
on  the  lever.  The  form  shown  in  Fig.  141  consists  of  a  single 
weight  suspended  from  the  valve  and  hanging  in  the  upper 


FIG.  141. — DEAD-WEIGHT  SAFETY-VALVE — WEIGHT  INSIDE  OF  BOILER. 

part  of  the  boiler.     This  form  is  to  be  commended,  since  it 
cannot  be  adjusted  without  opening  the  boiler. 

A  form  used  very  extensively  for  low-pressure  heating- 
boilers  consists  of  a  single  weight  resting  on  a  valve,  as  shown 
in  Fig.  142  ;  its  principle  of  operation  is  the  same  as  that  of  the 


ISO 


HEATING   AND    VENTILATING   BUILDINGS. 


other  valves.  A  form  much  used  on  power-boilers,  and 
frequently  called,  from  the  suddenness  with  which  it  opens,  a 
pop-valve  consists  of  a  very  quick-opening  valve  held  in  place 
with  a  spring,  one  form  of  which  is  shown  in  Fig.  143. 


FIG.  142.— EXTERNALLY  WEIGHTED 
SAFETY-VALVE. 


FIG.  143. — SECTION  OF  SPRING  OR  POP 
SAFETY-VALVE. 


It  is  desirable  that  the  safety-valve  be  made  in  such  a 
manner  that  the  engineer  or  attendant  to  the  boiler  cannot 
manipulate  it  at  pleasure  so  as  to  maintain  a  higher  pressure 
on  the  boiler  than  prescribed. 

Serious  accidents  have  been  caused  by  excessive  weighting 
of  the  safety-valve  through  ignorance  or  carelessness  on  the 
part  of  the  attendants,  and  for  this  reason  a  class  of  valves 
should  be  selected  which  cannot  be  tampered  with.  Some  of  ; 
the  safety-valves  are  provided  with  an  external  case  which  can 
be  locked,  and  others  are  provided  with  internal  weights,  as 
already  described.  The  lever  safety-valve  offers  the  most 
temptation  for  extra  weighting  and  should  rarely  be  used. 

The  area  of  a  safety-valve  must  be  sufficiently  large  to 
effectually  reduce  the  boiler  pressure  when  the  valve  is  open 
and  when  a  brisk  fire  is  burning  on  the  grate.  It  may  be 
computed  from  the  following  considerations : 

The  steam  which  will  flow  through  one  square  inch  of  open-  ] 
ing  in  one  hour  of   time  was  found   by  Napier*  to   equal  in  \ 


*Rankine's  "Steam  Engine." 


SETTINGS  AND   APPLIANCES, 


pounds  nearly  50  times  the  absolute  pressure  of  the  steam; 
further,  it  has  been  found  by  experiment  that  the  safety- 
valves  in  ordinary  use  open  only  to  such  an  extent  as  to  make 
\  of  the  total  area  of  the  valve  effective  in  reducing  the  press- 
ure. From  these  considerations  it  will  be  seen  that  the  area 
of  the  safety-valve  in  inches  should  be  -fa  the  weight  of 
steam  generated  per  hour,  divided  by  the  absolute  pressure. 
Considering  that  100  Ibs.  of  steam  can  be  generated  from  each 
square  foot  of  grate  per  hour,  this  would  be  equivalent  to  the 
following  rule:  The  area  in  square  inches  is  equal  to  18  times 
the  grate  surface  in  square  feet,  divided  by  the  absolute 
pressure. 

The  following  table  gives  the  area  of  safety-valve  in  square 
inches  per  square  foot  of  grate  required  on  marine  boilers  by 
the  English  Board  of  Trade : 


Boiler  Pressure. 

Boiler  Pressure. 

Absolute, 
Pounds  per 

Above 
atmos- 

Area in  square 
inches  for 
each  sq.  ft.  grate. 

Absolute. 

Above 
atmos- 

Area in  square 
inches  for 
each  sq.  ft.  grate. 

sq.  inch. 

phere. 

phere. 

15 

O 

1.25 

60 

45 

0.50 

20 

5 

1.07 

70 

55 

0.44 

25 

10 

0.94 

80 

65 

0.40 

30 

15 

0.83 

QO 

75 

0.36 

35 

20 

0-75 

100 

85 

0-33 

40 

25 

0.68 

no 

95 

0.30 

45 

30 

0.625 

120 

105 

0.277 

50 

35 

0.576 

130 

H5 

0.258 

The  following  formula  gives  results  very  closely  in  accord 
with  the  English  Board  of  Trade  table.  Let  A  =  area  of 
safety-valve  in  square  inches,  P  =  absolute  pressure  =  gauge 
pressure  plus  15,  G  =  number  of  square  feet  of  grate  surface. 


Various  rules  quite  different  from  the  above  are  given  in 
treatises  on  boiler  construction,  but  it  is  believed  that  the  above 
table  represents  the  best  practice  of  to-day  and  forms  a  safe 
guide  for  estimating  the  size  of  safety-valves. 

Safety-valves  are  liable  to  stick  fast  to  the  seat,  through 
corrosion,  in  which  case  they  fail  to  raise  with  excess  of  press- 


152  HEATING   AND     VENTILATING   BUILDINGS. 

ure  ;  for  that   reason  tliey  should  be  periodically  lifted   from 

their  seats  and  otherwise  inspected. 

In  case  the  area  of  the  valve  required  is  greater  than   4 

inches  in  diameter,  two  safety-valves  should  be  provided  for 

each  boiler. 

88.  Appliances  for  showing  Level  of  Water  in  the  Boiler. 

— In  the  first  boilers  constructed  floats  were  used,  and  such 
appliances  are  still  common  on  European  boil- 
ers. In  this  country  water-gauge  glasses  and 
try-cocks  are  now  used,  to  the  exclusion  of  all 
other  devices.  The  water-gauge  (see  Fig.  144), 
consists  of  two  angle-valves,  one  of  which  is 
screwed  into  the  boiler  above  the  water  line ; 
the  other  is  screwed  about  an  equal  distance 
below,  and  these  are  connected  by  means  of  a 
glass  tube  usually!  to  f  inch  external  diameter 
and  strong  enough  to  withstand  the  steam-press- 
ure. When  both  angle- valves  are  open  the  water 
will  stand  in  the  gauge-glass  the  same  height  as  in 
the  boiler,  but  if  either  valve  is  closed  the 
water-level  shown  in  the  glass  will  not  accord 
with  that  in  the  boiler.  Three  try-cocks  are 
usually  put  on  a  boiler  in  addition  to  the  water-; 
gauge.  The  try-cocks  are  made  in  various  forms, 
one  kind  being  shown  in  Fig.  145,  these  are 

located    so     that    one    is    above,    the    other 

FIG.  144. — GLASS  . 

WATER-GAUGE,  below,  and  the  third  at  about  the  mean  posi- 
tion of  the  water-line.  When  the  top  one  is  opened,  it 
should  show  steam  ;  when  the  bottom  one  is  opened  it,  should 


FIG.  145. — REGISTER  GAUGE-COCK. 

show  water.  Both  try-cocks  and  gauge-glasses  should  usually 
be  put  on  boilers,  so  that  the  reading  as  shown  in  the  water- 
gauge  glass  can  be  checked  from  time  to  time.  This  is  neces- 
sary, because  if  dirt  should  get  in  the  angle-valves  or  passages 


SETTINGS  AND    APPLIANCES. 


'53 


leading  to  the   gauge-glass  the  determination  would  be  inac- 
curate. 

Water-columns  attached  to  the  boiler  by  large  pipes,  both 
above  and  below  the  water-line,  and  fitted  with  try-cocks  and 
water-gauge  as  shown  in  Fig.  146,  are  often  provided.  These 
columns  frequently  contain  floats  (Fig.  147),  so  arranged  that 
steam  is  admitted  into  a  small  whistle  if  the  water  falls  below 
or  rises  above  the  required  limits,  and  thus  gives  an  alarm. 


FIG.  146. — WATER-COLUMN 


rics.  147. — RELIANCE  ALARM 
WATER-COLUMN. 


89.  Methods  of  Measuring  Pressure. — The  excess  of 
pressure  above  that  of  the  atmosphere  is  measured  by  some  form 
of  manometer  or  pressure-gauge. 
Where  the  pressure  is  small  in 
amount,  a  siphon,  or  U-shaped 
tube  rilled  with  some  liquid  is  a 
very  convenient  means  of  measur- 
ing pressure.  The  method  of 
using  a  simple  manometer  of  this 
character  is  shown  in  Fig.  148,  in 
which  a  U-shaped  tube,  G  F  E  D, 
has  one  branch  attached  to  the 
vessel  containing  the  fluid  whose 
pressure  is  to  be  measured ;  the 
other,  as  at  D,  is  open  to  the  air. 
If  water,  mercury,  or  other  liquid  be  placed  in  the  U-shaped 


E 

FIG.  148.— U-SHAPED  MA- 
NOMETER. 


154 


HEATING   AND    VENTILATING   BUILDINGS. 


tube  it  will  be  forced  down  on  the  side  of  the  greater  pressure 
and  upward  on  the  side  of  the  less,  a 
distance  proportional  to  the  pressure. 
The  height  of  the  fluid  in  one  side  in 
excess  of  that  on  the  other  will  be  a 
measure  of  the  difference  of  pressure  be- 
tween that  of  the  atmosphere  and  that 
in  the  vessel. 

Various  forms  of  manometers  are 
used,  of  which  several  are  shown  in  Fig. 
149.  For  very  low  pressures  water  is 
the  liquid  generally  employed;  for  mod- 
erate pressures  up  to  15  or  25  pounds 
mercury  is  very  convenient,  and  often 
used ;  while  for  high  pressures  a  pressure- 
gauge  (Fig.  150),  as  described  later,  is 
commonly  employed. 

The  Bourdon  pressure-gauge  is  or- 
dinarily used.  This  consists  of  a  tube 
of  elliPtical  cross-section  bent  into  a 
circular  form.  The  free  end  of  the  tube 

is  attached  by   gearing  to   a  hand  which   moves   over  a  dial. 

Pressure   on  the  interior  of  the  tube  tends  to  straighten  it,  and 


FIG.  150. — BOURDON  GAUGE 


moves  the  hand  an  amount  proportional  to  the  pressure. 

Fig.  150  shows  the  interior  of  a  pressure-gauge  of  this  char- 


SETTINGS  AND   APPLIANCES.  1 55 

.acter  with  the  dial  removed.  In  place  of  the  tube  a  corrugated 
diaphragm  is  sometimes  employed.  A  section  of  such  a  gauge 
is  shown  in  Fig.  151.  In  the  use  of  gauges  of  the  character  just 
described  it  is  necessary  to  protect  them  from  extreme  heat, 
this  purpose  when  they  are  connected  to  a  steam-boiler  a 


FIG.  151. — DIAPHRAGM  GAUGE. 

siphon  or  U-shaped  form  of  pipe  is  to  be  used  in  the  connec- 
tion, so  that  water  and  not  steam  will  be  forced  into  the  inte- 
rior of  the  gauge. 

The  manometers  and  gauges  described  in  every  case  measure 
the  pressure  above  or  below  that  of  the  atmosphere.     If  they 
[measure  a  pressure  lower  than  that  of  the  atmosphere  they  are 
commonly  called  vacuum-gauges,  but  the  principle  of  construc- 
tion is  the  same  as  described. 

The  relations  of  various  units  used  in  measuring  pressure 
•can  be  readily  determined  from  the  following  table  of  equiva- 
lents :  i  inch  of  mercury  —  13.619  inches  of  water  =  1.134  feet 
[of  water  =  0.49101  pound  =  399.51  feet  of  air  at  60  degrees 
Fahrenheit  and  barometer  pressure  30  inches.  The  pressures 
are  usually  taken  as  acting  on  one  square  inch  of  a  body. 


156 


HEATING   AND    VENTILATING   BUILDINGS. 


90.  Thermometers.— The  methods  of  constructing  various 
kinds  of  thermometers  have  been  described  in  Articles  8  to  12. 
In  any  hot-water  heating  system  it  is  quite  important  to  know 
the  temperature  of  the  water  leaving  the  heater,  and  in  many 
cases  also  that  of  the  return.  This  information, 
while  not  so  vital  to  the  safety  of  the  heater  as 
that  given  by  a  pressure-gauge  on  a  steam-heat- 
ing system,  is  of  the  same  character,  and  will 
prove  to  be  equally  valuable  in  indicating  the 
work  done  by  the  heater,  and  the  heat  absorbed 
by  the  system. 

Any  of  the  suitable  forms  described  in  Chap- 
ter I  can  be  used,  but  special  forms  in  which 
the  thermometer-bulb  sets  in  a  cup  of  mercury 
(Fig.  152)  are  often  used,  the  cup  being  screwed 
into  the  pipe  whose  temperature  is  required. 
These  thermometers  should  be  set  so  as  to  ex- 
tend deep  into  the  current. of  flowing  water, 
and  there  should  be  no  opportunity  for  air  to 
gather  around  the  bulb  ;  otherwise  the  readings 
will  not  be  the  true  temperature. 

91.  Damper-regulators.— Nearly  all  steam- 
boilers  are  provided  with  an  apparatus  for  open- 
ing or  closing  the  dampers  and  draft-doors  to 
the  boiler  as  may  be  required  to  maintain  a 
constant  steam-pressure.  For  low-pressure 


FOR  steam-heating  plants  the  regulator  consists  in 


FIG.  152.— THER- 
MOMETER     FOR 

HOT  -WATER 

HEATING.  nearly  every  case  of  a  rubber  diaphragm  (tig. 

153),  which  receives  the  steam-pressure  on  one  side,  and  acts 
against  a  counter-weight  resting  on  a  plate  on  the  opposite 
side.  The  plate  is  connected  by  a  rod  to  a  lever  pivoted  to  the 
external  case,  which  in  turn  is  connected  to  the  various  drafts 
by  means  of  chains,  and  so  arranged  that  if  the  pressure 
rises  the  lever  is  lifted  and  the  drafts  closed,  while  if  the  press- 
ure falls  the  lever  also  falls,  and  the  drafts  are  opened.  By 
means  of  weights  on  the  lever  the  regulator  can  be  set  to 
operate  at  any  pressure.  The  regulator  should  be  connected 
to  the  boiler  below  the  water-line,  or  by  means  of  an  U-shaped 
pipe,  arranged  so  that  the  part  of  the  vessel  below  the  dia- 


SETTINGS  AND   APPLIANCES.  1 57 

phragm  will  remain  full  of  water ;  otherwise  the  heat  in  the 
steam  will  cause  the  rubber  to  deteriorate  rapidly.  The  form 
shown  in  Fig.  153  is  so  arranged  that  the  diaphragm  must  in 
every  case  be  in  contact  with  water. 

While  rubber  diaphragms  are  usually  durable  for  low-pres- 
sure steam-regulators,  still  they  occasionally  are  ruptured.  In 
order  to  prevent  accident  from  such  a  cause,  the  Nason  Manu- 
facturing Co.  have  devised  a  form  of  such  a  character  that  the 
draft-doors  will  close,  instead  of  open,  in  case  of  rupture.  This 
is  done  by  using  a  link  in  the  connecting-chain  to  the  draft- 
doors  of  some  metal  that  will  be  fused  at  a  temperature  below 
that  of  boiling  water,  and  arranged  so  that  in  case  of  rupture 
the  escaping  steam  and  hot  water  will  impinge  upon  and  melt 
it  ;  the  damper  will  be  closed  by  its  own  weight  when  the 
link  breaks. 

Damper-regulators  for  high-pressure  steam  are  constructed 
so  as  to  operate  on  the  same  principle  as  those  described,  but 
instead  of  a  rubber  diaphragm  either  a  metallic  diaphragm  or  a 
piston  working  in  a  cylinder,  and  operated  by  water-pressure, 
is  employed. 

The  following  cut  shows  the  external  appearance  of  one  of 
the  many  forms  in  use. 


FIG.  153. — DIAPHRAGM  FIG.  154. — PISTON  DAMPER-REGULATOR. 

DAMPER-REGULATOR. 

92.  Blow-off  Cocks  or  Valves.— Every  steam-boiler  should 
be  provided  with  an  appliance  for  emptying  all  of  the  water  at 
any  time.  This  may  be  done  by  leading  a  pipe  from  the  lowest 
part  of  the  boiler  and  providing  a  cock  or  valve  so  that  it  can 
be  discharged  at  pleasure.  The  pipe  leading  from  the  boiler 
should  have  a  visible  outlet,  so  in  case  there  is  any  leak  it  can 


HEATING  AND    VENTILATING   BUILDINGS. 


be  seen  and  stopped.  The  writer  prefers  a  cock  (Fig.  155)  toj 
a  valve  for  use  on  the  blow-off  pipe,  since 
it  is  less  likely  to  be  stopped  by  scale  or 
sediment  from  the  boiler. 

In  case  the  water  of  condensation  from 
the  heating  coils  is  not  returned  to  the 
boiler  it  is  necessary  to  blow  off  some  of 
the  water  very  frequently  in  order  to  lessen 
the  deposition  of  scale  or  dirt  on  the  bottom 
of  the  boiler. 

93.  Expansion-Tank. — An  expansion- 
tank  will  be  needed  in  hot-water  heating 

of 


FIG.  155. — PACKED 
PLUG  COCK. 


systems.  With  increase  of  temperature 
from  40°  F.  to  the  boiling-point,  water 
expands  4.66  parts  in  100,  or  nearly  5  per  cent.  The  force 
of  expansion  is  nearly  irresistible,  and  the  increase  in  volume 
due  to  it  must  be  provided  for,  so  as 
not  to  produce  a  dangerous  press- 
ure. 

The  method  ordinarily  adopted  con- 
sists in  the  use  of  a  vessel  called  an 
expansion-tank,  whose  cubical  contents 
must  be  somewhat  greater  than  one 
twentieth  of  the  total  cubical  contents 
of  heater,  pipes,  and  radiators.  It 
must  be  connected  to  the  heating  sys- 
tem in  such  a  way  as  to  receive  the  in- 
crease in  volume,  and  should  be  placed 
on  a  level  somewhat  above  that  of  the 
highest  radiating  surface. 

If  there  is  to  be  no  sensible  increase 
in  pressure  due  to  expansion  the  tank 
is  connected  with  the  outside  air  by  a 
vent-pipe,  and  in  this  case  the  pressure 
inside  will  be  atmospheric  ;  the  pressure 
on  the  heating  system  will  depend  on  the  distance  from  the 
water-level  in  the  tank,  each  foot  corresponding  to  0,435  pounds 
per  square  inch  (2.4  feet  being  equivalent  to  one  pound  oi 
pressure  at  212°  F.). 


FIG.  156.  EXPAN- 
SION-TANK. 


SETTINGS  AND    APPLIANCES 


'59 


In  case  a  pressure  in  excess  of  the  atmosphere  is  required, 
the  vent  pipe  is  closed  and  a  safety-valve  attached  which  will 
open  when  the  pressure  reaches  the  desired  point.  By  increas- 
ing the  pressure  on  the  system  the  boiling  temperature  of  the 
water  will  be  much  increased,  and  hence  it  will  be  possible  to 
^maintain  a  higher  temperature  throughout  the  system.  As 
showing  the  increase  in  temperature  of  the  boiling  point  with 
excess  of  pressure,  the  following  table  is  inserted  : 


Pressure. 

Pounds 
per  sq.  in. 
above 

Equivalent  Head, 
in  Feet. 

Temperature  of 
Boiling  Point 
(degrees  F.). 

Atmosphere. 

O 

O 

212 

5 

12 

228 

.  .  .  •      10 

24 

240 

15 

3^ 

250 

20 

43 

259 

25 

60 

267 

30 

72 

274 

35 

84 

280 

40 

96 

287 

45 

1  08 

292 

50 

1  20 

297 

55 

132 

302 

60 

M4 

307 

70 

168 

3«6 

-      80 

192 

324 

90 

216 

332 

IOO 

240 

338 

125 

300 

352 

150 

360 

365 

175 

420 

378 

200 

480 

388 

Pressure  systems  of  hot-water  heating  were  used  at  one 
time  to  a  considerable  extent  in  England,  under  what  was 
known  as  the  Perkins*  system,  in  which  small  pipes  and 
exceedingly  high  pressures  and  temperatures  were  used.  It 
has  also  been  used  to  some  extent  in  this  country  in  the  Baker 
system  of  car-heating. 

The  advantages  of  the  pressure  system  are  those  which  are 
due  simply  to  the  use  of  higher  temperatures  and  smaller  radi- 
cating surfaces ;  the  disadvantages  are  the  danger  of  an  explosion 


*  Hood's  "  Heating  and  Ventilating  of  Buildings." 


160  HEATING   AND    VENTILATING   BUILDINGS. 

which  would  be  likely  to  happen  were  the  safety-valve  inoper! 
ative,  or  did  any  part  of  the  apparatus  give  way.  The  sudden 
liberation  of  a  considerable  body  of  water  having  a  temperatun 
above  the  boiling  point  would  result  in  the  instantaneous  prof 
duction  of  a  large  amount  of  steam,  which  might  produce  disl 
astrous  results. 

With  the  open  expansion-tank  it  seems  hardly  possible  thaw 
any  serious  accidents  could  result  even  from  the  most  carelesil 
management,  since  the  escape  of  steam  from  the  top  of  thet 
expansion-tank  would  prevent  the  accumulation  of  pressure,! 
To  prevent  accident  the  expansion-tank  should  be  connected 
to  the  heater  by  a  pipe  protected  from  frost  and  without! 
stop  or  valve,  so  as  to  render  it  impossible  to  increase  the] 
pressure  on  the  system  by  stoppage  of  the  connection. 

It  is  desirable  to  provide  the  expansion-tank  with  a  glass 
water-gauge  showing  the  depth  of  water,  and  a  connection  tc 
the  supply-pipe  for  adding  water  to  the  system.  In  case 
the  expansion-tank  occupies  a  cold  location  where  it  might 
freeze  in  extreme  weather,  a  small  pipe  connected  with  thei 
circulating  system,  in  addition  to  those  described,  should  be 
run  to  the  tank  and  connected  at  a  higher  level  than  the  ex- 
pansion-pipe, so  as  to  insure  circulation  of  warm  water. 

94.  Form  of  Chimneys. — The  form  and  size  of  the  chim* 
ney  is  of  great  importance  in  connection  with  the  satisfactory! 
operation  of  a  heating  plant,  and  it  should  in  every  case 
receive  the  closest  inspection  before  guarantees  of  capacity  arm 
made. 

It  will  be  found  that  for  a  specified  area  a  round  chimney 
will  have  the  most  capacity,  but  in  ordinary  building  construe! 
tion  such  a  chimney  is  difficult  to  construct  and  is  not  ordi^ 
narily  built.  A  square  chimney  of  the  same  area  has  some* 
what  more  friction,  and  one  with  a  rectangular  narrow  fluJ 
very  much  more,  so  that  an  increase  in  area  proportional  to  ex| 
cess  of  perimeter  should  be  made  for  such  cases.  The  chimneyf 
should  be  as  smooth  as  possible  on  the  inside  in  order  to  prej 
vent  loss  of  velocity  by  friction,  and,  if  of  brick,  the  flue  should 
in  every  case  be  plastered.  In  the  construction  of  chimneys  it 
is  better  that  the  inside  be  made  with  a  thin  wall  not  con- 
nected in  any  way  with  the  outside,  both  in  order  to  permit 


SETTINGS  AND   APPLIANCES.  l6l 


free  expansion  of  the  inner  layer  of  the  chimney  with  the  heat 

and  also  to  secure  the  advantage  of  the  non-conducting  power 
[of  an  air  space  between  the  inside  and  outside  walls.  Such  a 

construction  is  common  for  chimneys  for  power  purposes,  but 

is  not  ordinarily  applied  to  those  used  in  buildings. 

95.  Sizes  of  Chimneys.  —  The  area  of  cross-section  required 

for  a  given  chimney  will  depend  upon  its  height  and  also  upon 
[the  amount  of  coal  to  be  burned.  The  conditions  which  affect 

chimney  draft  are  so  numerous,  and  so  difficult  to  consider  in 
[any  theoretical  discussion,  that  empirical  or  practical  formulae 
[derived  from  the  study  of  actually  existing  plants  are  prob- 
ably more  satisfactory  than  those  obtained  from  purely  theo- 
Iretical  computations.  Of  the  various  formulae  which  have 
peen  given  for  the  capacity  of  chimneys  the  writer  prefers 

that  of  William  Kent,  from  which  the  accompanying  table  is 

computed. 

Kent's  formula  is  computed  on  the  assumption  that  the  chimney  shall  have 
a  diameter  two  inches  greater  than  that  required  for  passage  of  the  air,  in  order 
to  compensate  for  friction.  The  following  is  his  formula  : 


S=    12    tf£ 

h  = 


;in  which  A  —  actual  area  in  square  feet  of  the  chimney,  £=  effective  area, 
h  =  height  in  feet,  S  —  side  of  the  square  in  inches,  H  =  horse-power  of  plant. 
If  we  let  fi  =  number  of  square  feet  of  radiating  surface  to  be   supplied, 
then,  Article  73,  page  173, 


.003!? 
from  which  E  = —  - 


The  table  gives  the  diameter  of  round  or  side  of  square  chimneys  in  inches 
for  various  heights  computed  from  the  above  formulae,  with  the  diameter  in- 
creased by  2,  to  allow  for  friction.  A  square  chimney  is  considered  the 
equivalent  of  the  inscribed  round  one. 


162 


HEATING   AND    VENTILATING   BUILDINGS. 


DIAMETER    OR   SIDE    OF    CHIMNEY    IN    INCHES  REQUIRED  FOR 
VARYING  AMOUNTS  OF  DIRECT  STEAM-RADIATING  SURFACE. 


Height  of  Chimney  in  Feet 

20 

30 

40 

50 

60 

80 

100 

120 

Square  Feet  of 
Steam  Ra- 

Horse- 

diation. 

power. 

250 

2.5 

7-4 

7.0 

6.7 

6.4 

6.2 

6.0 

6.0 

6.0 

500 

5.0 

9.6 

9.2 

8.8 

8.2 

8.0 

6.6 

7-3 

7.0 

750 

7.5 

ii.  3 

10.8 

10.2 

9.6 

9-3. 

8.8 

8.5 

8.2 

I,OOO 

10.0 

12.8 

12.  0 

ii.  4 

10.8 

10.5 

10.  0 

9-5 

9-2 

1,500 

15.0 

15-2 

14.4 

13-4 

12.8 

12.4 

ii  5 

II  .2 

10.8 

2,000 

20.0 

17.2 

I6.3 

15-2 

14.5 

14.0 

13-2 

12.6 

12.1 

3,000 

30.0 

20.  6 

I8.5 

IS.2 

17.2 

16.6 

15-8 

15.0 

14.4 

4,000 

4O.O 

23.6 

22.2 

20.8 

19.6 

19.0 

17.8 

17.0 

16.3 

5,000 

5O.O 

26.0 

24.6 

23.0 

21.6 

21  .0 

19.4 

18.6 

18.0 

6,000 

60.0 

28.4 

26.8 

25.0 

23.4 

22.8 

21.2 

2O.  2 

19-5 

7,000 

7O.O 

30-4 

28.8 

27.0 

2^.5 

24.4 

23.0 

21  .6 

20.8 

8,000 

So.o 

32-4 

30.6 

28.6 

26.8 

26.O 

24.2 

23-4 

22.2 

9.000 

90.0 

34-0 

32-4 

30.4 

28.4 

27.4 

25.6 

24.4 

23-4 

10,000 

IOO.O 

37-0 

34-0 

32.0 

30.0 

28.6 

27.O 

25-4 

24.6 

I  ^  OOO 

I^O   O 

18   4 

-16.2 

•2C  .0 

•2-2      O 

•21    O 

2Q    2 

1  D><~'v-'v-' 
20,000 

fc  y*  .  ^ 
2OO.O 

O^  •  *T 

4-T.O 

o 

42.0 

j  j  •  w 
41  .0 

JO  '  ^ 

1.-]  .0 

j  i  .  v/ 

•ic    O 

**f  •  *• 

34  O 

30,000 

3OO.O 

*T  J      W 

50.0 

48.0 

J  1  '  w 

46.0 

3D  '  w 

43-o 

•}*T  *  v^ 
41.0 

For  other  kinds  of  heating  multiply  the  radiating  surface  by  the  following 
factors  :   Hot- water  heating  1.5,  indirect  steam  0.7,  hot-blast  heating  0.2. 

96.  Chimney-tops. — The  draft  of  a  chimney  is  influenced! 
to  a  great  extent  by  the  conditions  of  the  surrounding  space. 
If  other  buildings  exist  in  the  vicinity  of  such  a  form  as  to  de- 
flect the  currents  of  air  down  the  chimney,  the  draft  will  bej 
impaired  and  may  be  entirely  destroyed.  The  objects  which] 
tend  to  produce  downward  air-currents  may  sometimes  be 
situated  a  considerable  distance  from  the  chimney  and  thus  ren- 
der the  specific  cause  of  poor  draft  very  difficult  to  determine.! 
The  remedy  for  a  smoky  chimney  is  sometimes  difficult  to  ap-1 
ply,  but  usually  the  draft  will  be  improved,  first,  by  increasing; 
the  height  of  the  chimney ;  second,  by  adopting  some  form  of, 
chimney-top  which  utilizes  the  force  of  horizontal  currents  to 
aid  by  induction  in  increasing  the  draft. 

The  writer  found  that  curved  trumpet-shaped  tubes  located! 
with  the  small  ends  projecting  into  the  chimney  in  an  upwarJ 
direction  increased  the  draft  materially  when  the  wind  was 
blowing  into  the  openings,  and  there  is  little  reason  to  doubt; 
but  that  a  chimney-top  may  be  constructed  in  such  a  manner 
as  to  materially  increase  the  draft. 


SETTINGS   AND    APPLIANCES.  163 

97.  Grates. — For  supporting  the  fuel  during  its  combus- 
tion in  such  a  manner  as  to  allow  a  free  passage  of  air,  a  per- 
forated metallic  construction  of  some  sort  is  required.  For 
burning  very  fine  coal  the  perforation  must  be  small  and  close 
together  ;  for  burning  larger  sized  coal  the  perforations  may  be 
larger  and  further  apart.  The  area  of  the  air-spaces  compared 
with  the  total  area  of  the  grate  should  be  about  50  per  cent  in 
order  to  secure  best  results,  but  they  will  more  generally  be 
found  to  be  30  to  40  per  cent.  The  grates  are  usually  con- 
structed of  cast  iron  and  in  a  very  great  variety  of  forms, 
jas  shown  in  Figs.  157  and  158.  In  some  instances  a  series  of 
parallel  bars  is  used  ;  in  others  the  grates  are  made  in  one  solid 


FIG.  157.  DIFFERENT  FORMS  OF  GRATES. 


casting.  This  latter  practice  is  never  one  to  be  recommended. 
The  solid  grate  is  likely  to  break  from  expansion  strains  due  to 
heating  unless  made  in  such  form  that  the  various  parts  are 
free  to  expand  independently. 

Nearly  all  heating-boilers,  hot-water  heaters,  and  furnaces 
are  supplied  with  some  form  of  shaking-  and  dumping-grate. 
Many  of  these  grates  are  known  from  experience  of  the 
writer  to  give  most  excellent  satisfaction,  and  doubtless  all 
present  points  of  merit.  The  various  shaking-grates  operate 
in  nearly  every  way,  and  it  is  hard  to  conceive  either  a  form  of 
grate-bar  or  a  method  of  shaking  which  is  not  exemplified  in 
some  of  these  grates.  Some  of  the  bars  are  flat  or  rectangular 
in  shape,  and  are  operated  by  shaking  backward  and  forward  ; 
others  are  triangular  and  are  continually  rotated  so  as  to  pre- 
sent successively  new  surfaces  to  the  fire  each  time  they  are 
shaken.  The  shaking-grate  will,  in  general,  be  found  much 
superior  to  the  fixed  one,  and  a  furnace  fitted  with  such  grates 


164 


HEATING   AN£>    VENTILATING   BUILDINGS. 


is  more  easily  managed  and  more  cleanly  than  one  with  a  fixed 
grate  of  any  description. 

98.  Traps. — In  all  systems  of  gravity  steam-heating,  the 
water  of  condensation  returns  directly  to  the  boiler,  and  no 
appliance  either  for  maintaining  a  water-line  in  the  building  or 
returning  the  condensed  steam  to  the  boiler  is  required.  But 
there  are  cases  in  which  it  is  necessary  to  maintain  the  water- 
line  at  a  certain  definite  height,  and  also  to  prevent  the  escape 
of  steam  without  interfering  with  the  discharge  of  condensing 
water.  For  this  purpose  a  steam-trap  is  re- 
quired. One  form  of  a  steam-trap  which  has 
always  been  used  to  a  greater  or  less  extent  for 
this  purpose  is  a  siphon  made  in  the  shape  of 
'0  a  U  bend,  or  its  equivalent  of  pipe  and  fit- 
tings, as  shown  in  Fig.  159.  It  consists  of  two 
legs,  AB  and  BC,  which  may  be  close  to- 
gether or  any  distance  apart,  but  the  length  of 
which  must  be  sufficiently  great  to  prevent 
pressure  acting  through  the  pipe  FA  forcing 
the  water  out  of  BC.  CE  is  a  vent-pipe  ex- 
tending to  the  air ;  D  is  the  discharge  for  the 
condensed  water.  In  ordinary  operation  the 
leg  CB  is  filled  with  water  which  is  constantly 
overflowing,  and  AB  with  steam  and  water;  the  total  pressure 
in  both  legs  being  in  each  case  equal. 

The  siphon-trap  may  be  open  to  the  objection  that  it  will 
require  a  great  deal  of  vertical  room   if  the  pressure  is  great ; 


FIG.  159. 
SIPHON-TRAP. 


FIG.   1 60.—  FLOAT-TRAP. 


for  this  reason  traps  with  mechanical  movements  of  some  kin< 
are  usually  preferred.     The  simplest  of  these  traps  contains 
float  (Fig.  160)  which  rises  and  falls  with  change  of  level  of  th< 


SETTINGS  AND   APPLIANCES. 


i65 


water  in  the  vessel.  Rising  above  a  certain  point,  it  opens  a 
discharge-valve  ;  falling  below,  it  closes  it.  Traps  of  this  class 
are  made  of  a  great  many  designs.  In  some  instances  traps 
are  made  as  in  Fig.  161,  in  which  a  weight  W  \s  used  instead  of 


FIG.   161. — COUNTER-WEIGHTED  TRAP. 

a  float  and  is  nearly  counter-balanced  by  the  weight  D.  As  the 
water  rises  in  the  trap  it  tends  to  lift  the  weight  PFan  amount 
proportional  to  its  volume,  thus  opening  a  discharge-valve  at^. 
When  the  water  falls,  the  valve  is  closed.  It  is  noted  that 
the  counter-weight  D  is  always 
above  the  water-line  P. 

A  large  number  of  traps  are 
made  with  a  hollow  metallic  float 
or  bucket,  so  arranged  as  to  open 
a  valve  when  the  bucket  is  full  of 
water.  One  form  is  shown  in 
Fig.  162,  in  which  the  water 

enters  the  trap  at  A,  filling  the  FIG.  162.— BUCKET  TRAP. 

space  5  between  the  bucket  and  the  walls  of  the  trap.  This 
causes  the  bucket  to  float,  and  thus  to  close  an  orifice  in  the 
discharge-pipe  V.  When  the  water  rises  above  the  edges  of  the 
bucket  it  flows  into  it  and  causes  it  to  sink,  which  opens  the 
discharge-valve  at  V.  The  water  is  forced  out  through  the  pipe 
B  by  the  steam  pressure  acting  on  the  surface  55. 

The  bucket  traps  are  made  in  great  variety,  both  as  to 
form  of  valve,  guides  for  bucket,  etc.  Fig.  163  shows  one 
of  the  traps  which  is  in  common  use,  with  all  details  of  con- 
struction. 

Another  extensive  class  of  traps  are  made  so  as  to  be  closed 
by  the  expansion  due  to  increase  in  temperature.  These  traps 
differ  from  each  other  very  much  in  form  ;  the  principle,  how- 


i66 


HEATING   AND    VENTILATING   BUILDINGS. 


ever,  is  in  all  cases  the  same.  Thus  in  the  diagram,  Fig.  164, 
steam  is  supplied  at  A  and  discharged  at  B.  The  bent  springs 
5  are  prevented  by'guides  from  moving  laterally,  so  that  the 
expansion  due  to  heat  causes  a  motion  which  closes  the  orifice 
in  the  discharge-pipe  B.  When  the  water  in  the  traps  cools 


FIG.   163.— BUCKET  TRAP. 

the  valve  opens.  The  materials  used  for  traps  of  this  clase 
can  be  metallic  or  some  composition  of  material  like  that  em- 
ployed for  air-valves.  The  discharge  can  be  arranged  to  tak< 
place  from  the  bottom  or,  as  sho\vn  in  the  diagram,  from  tin 
side. 


FIG.  164.— EXPANSION-TRAP. 

Traps  which  combine  one  or  more  of  the  principles  oi 
operation  as  described  are  on  the  market.  Thus  Fig.  165  re] 
resents  a  trap  with  two  valves  in  which  one  valve  is  opened  b; 
expansion,  the  other  by  a  float. 

The  bucket  traps  have  generally  proved  the  most  reliabl< 
and  less  likely  to  be  injured  by  use.  The  float-traps  have  beei 
liable  to  failure  because  of  leakage  of  the  float,  but  receni 
improvements  in  manufacture  render  this  accident  quite  im 


SETTIA-GS   AND    APPLIANCES. 


I67 


probable.  All  traps  need  periodical  inspection,  as  the  valves 
are  likely  to  become  more  or  less  choked  up,  in  which  case 
the  trap  may  fail  to  operate.  All  of  the  traps  described 


FIG    165. — COMBINED  FLOAT-  AND  EXPANSION-TRAP. 

will  discharge  the  water  to  a  height  which  corresponds  to  the 
steam-pressure  in  use,  and  hence  when  used  with  high-pressure 
steam  will  lift  water  to  a  considerable  distance;  but  in  no  case 
will  they  return  the  water  into  the  boiler  from  which  the  steam 
was  received.  For  this  purpose  a  trap  of  considerable  more 
complexity,  known  as  a  return-steam  trap,  must  be  used. 

99.  Return-traps. — Traps  which  receive  the  water  of  con- 
densation and  return  it  to  a  boiler  having  considerably  higher- 
*pressure  steam  than  that  acting  on  the  returns,  are  known  as 


c' 


FIG.  1 66. —DIAGRAM  SHOWING  ACTION  OF  RETURN-TRAP. 

return-traps.  They  are  made  in  quite  a  variety  of  forms,  but 
the  general  principle  of  operation  is  shown  by  the  diagram 
Fig.  1 66.  In  this  figure  D  represents  the  boiler  and  AB  the  trap, 


i68 


HEATING   AND    VENTILATING   BUILDINGS. 


which  is  located  above  the  boiler  and  is  supplied  with  steam 
from  the  boiler  at  A.  It  is  connected  with  the  return  system 
by  a  pipe  leading  from  the  tank  or  drum  P,  and  pipe  dis- 
charging into  the  trap  at  E.  A  pipe  leads  from  the  bottom  of 
the  trap  B  and  connects  below  the  water-line  with  the  boiler. 
Check-valves  are  located  at  C  and  C,  which  permit  the  flow  to 
take  place  toward  the  boiler  only.  The  essential  method  of 
operation  of  the  trap  is  as  follows  :  First,  water  flows  into  the 
trap  from  the  return  P,  until  it  reaches  a  certain  level,  when 
it  acts  on  the  float  B  so  as  to  open  a  balanced  steam-valve, 


FIG.  167, — BUCKET  RETURN-TRAP. 

called  an  equalizing-vavle,  connected,  to  the  main  pipe  A.  This 
permits  steam  from  the  boiler  to  enter  the  trap,  which  equal 
izes  the  pressure  of  steam  in  the  trap  and  boiler.  The  watei 
in  the  trap,  because  of  its  greater  density,  then  commences 
to  flow  out  through  the  pipe  B,  and  need  only  cease  when 
the  level  becomes  nearly  the  same  as  in  the  boiler.  The  dis 
charge  of  the  wafer  causes  the  float  B  to  fall,  which  closes  the 
equalizing  valve,  and  the  operation  as  described  is  again  re- 
-peated. 

Instead   of   a  float  a  bucket  may  be  used  to  operate  the 


SETTINGS  AND   APPLIANCES. 


169 


equalizing-valve,  acting  in  a  manner  similar  to  that  described 
for  the  ordinary  bucket  trap.  A  section  of  such  a  trap  is 
shown  in  Fig.  167. 

The  bucket  is  probably  superior  to  the  float  for  this  pur- 
pose, since  it  is  less  likely  to  be  affected  in  its  operation  by 
change  in  density  or  pressure  of  the  steam. 

Various  other  systems,  for  opening  and  closing  the  equaliz- 
ing-valve have  been  adopted,  of  which  one,  shown  in  Fig.  168, 


FIG.  168. — GRAVITATING  RETURN-TRAP. 

^consists  in  mounting  the  trap  so  that  it  will  move  into  one 
position  when  empty  and  into  another  when  full,  the  motion 
350  obtained  being  used  to  open  and  close  the  equalizing-valve. 
A  different  construction  for  accomplishing  the  same  pur- 
pose is  shown  in  Fig.  169. 


FIG. 


[69  — RETURN-TRAP. 

ioo.  General  Directions  for  the  Care  of  Steam-heating 
Boilers. — Special  directions  will  be  no  doubt  supplied  by  the 


HEATING   AND    VENTILATING   BUILDINGS. 

maker  for  each  kind  of  boiler,  or  for  those  which  are  to  be 
managed  in  a  peculiar  way.  The  following  directions  are  gen- 
eral  and  should  always  be  observed,  regardless  of  the  kind  of 
boiler  employed  : 

1.  Before  starting  the  fire  see  that  the  boiler  contains  water. 
Its  surface  should   stand  a  distance  of  from  one  third  to  one 
half  the  height  of  the  gauge-glass. 

2.  See  that  the  smoke-pipe  and  chimney-flue  are  clean  and 
that  the  draft  is  good. 

3.  Build  the  fire  in  the  usual  way,  using  a  quality  of  coal 
which  is  adapted  to  the  heater. 

4.  In  operating  the  fire  keep  the  fire-pot  full  of  coal  and 
shake  down  and  remove  all   ashes  and   cinders  as  often  as  the 
state  of  the  fire   requires  it.     If  a  magazine  heater  is  used  it 
must  be  kept  full  of  coal. 

5.  Hot  ashes  or  cinders  must  not  be  allowed  to  remain   in 
the  ash-pit  under  the  grate-bars,  but  must  be  removed  at  stated; 
intervals  to  prevent  burning  out  of  the  grate. 

6.  To   control  the  fire,  see   that  the  damper   regulator  is 
properly  attached  to  draft-doors  and  damper;  then  regulate  the 
draft  by  weighting  automatic  draft-lever  as  required,  lightly  or 
not  at  all  in  mild  weather,  but  increasing  as  the  weather  be- 
coming colder. 

7.  Should  the  water  in   the   boiler  escape,  by  means  of  a 
broken  gauge-glass  or  other  mishap,  it  will  be  safer  to  dump 
the  fire  and  let  the  boiler  cool  before  letting  in  cold  water. 

In  no  case  should  an  empty  boiler  be  filled  wlien  hot.  If  the 
water  gets  low,  but  not  out  of  sight,  in  the  gauge-glass,  extra 
water  may  be  added  at  any  time  by  the  means  provided  for 
this  purpose. 

8.  Occasionally  lift  the  safety-valve  from  its  seat  to  see  that 
it  is  in  good  condition. 

9.  Clean  the  boiler,  if  used  in  a  gravity  system  of  circulation, 
once  each  year  by  filling  with  pure  water  and  emptying  througl 
the  blow-off  pipe.     If  the  steam  is  used  largely  for  power,  the 
boiler  must  be    cleaned  at   frequent    intervals.     In    case   the; 
boiler  should  become  foul  or  dirty  it  can  be  thoroughly  cleaned 
by  adding  a  few  pounds  of   caustic  soda  and  allowing  it  to 
stand  one  day,  then  emptying  and  thoroughly  rinsing.     Kero- 
sene oil  will  loosen  boiler  scale  and  not  injure  the  boiler,  but] 


SETTINGS  AND   APPLIANCES.  I /I 

its  odor  will  be  quite  likely  to  penetrate  the  whole  building  in 
which  the  heating  system  is  located. 

10.  During  the   summer  months   the  writer  would  recom- 
mend that  all  the  water  be  drawn  off  from  the  system  and  that 
air-valves  and  safety-valves  be  opened,  to  permit  the  heater  to 
dry  out  and  remain  so.     Good  results  are,  however,  obtained 
by  filling  the  heater  full  of  water,  driving  off  the  air  by  boil- 
ing slowly,  and  allowing  it  to  remain  in  this  condition  until 
needed  in  the  fall.     The  water  should  then  all  be  drawn  off  and 
fresh  water  added. 

11.  Keep  the  fire  surfaces  of  the  boiler  clean  and  free  from 
soot.     For  this  purpose  a  brush  is  provided  with  most  heaters. 

12.  In  case  any  of  the  rooms  are  not  heated,  look  out  for 
the  steam-valves  at  the  radiators.     If  a  two-pipe  system,  both 
valves  at  each  radiator  must  be  opened  or  closed  at  the  same 
time,  as  required.     See  that  the  air-valves  are  in  proper  condi- 
tion.    If  a  one-pipe  system,  one  valve  only  has  to  be  opened 
or  closed. 

13.  If  the  building  is  left  unoccupied  in  cold  weather,  draw 
all  the  water  out  of  the  system,  which  can  only  be  done  by 
opening  blow-off  pipe,  all  radiators,  and  air-valves. 

101.  Care  of    Hot-water    Heaters. — The  general  direc- 
tions for  the  care  of  steam-heating  boilers,  Article  100,  apply  in 
a  general  way  to  hot-water  heaters  as  to  the  methods  of  caring 
for  the  fires  and  for  cleaning  and  filling  the  heater.     The  special 
points  of  difference  only  need  to  be  considered.     All  the  pipes 
and  radiators  must  be  full  of  water  and  the  expansion-tank 
should  contain  some  water, as  shown  by  the  gauge-glass  or  by  the 
pressure-gauge;  and  this  condition  should  be  determined  before 
building  a  fire  and  whenever  visiting   the  heater  for  the   pur- 
pose of  replenishing  the  fuel.     Should  any  of  the  radiators  not 
circulate,  see  that  the   radiator  valve   is  open  then  open   air- 
valve  until  the  water  runs  out,  after  which   it  must  be  closed 
tight.     Water  must    always  be  added  at  the  expansion-tank 
when  for  any  reason  it  is  drawn  from  the  system. 

102.  Boiler  Explosions.  —  Boiler   explosions    sometimes 
occur  with  disastrous  results.     They  are  not  limited  to  boilers 
in  which  high-pressure  steam  is  employed,  but  also  occur  in 
some  instances  with  low-pressure  boilers  employed  in  heating. 


172  HEATING   AND    VENTILATING   BUILDINGS. 

The  cause  of  a  steam-boiler  explosion  is  in  every  ease 
an  excess  of  pressure  above  that  of  the  strength  of  the  boiler. 
The  effect  of  this  is  primarily  to  rupture  a  part  or  portion  of 
the  boiler,  relieving  the  pressure  on  the  side  of  the  rupture. 
This  leaves  unbalanced  all  the  pressure  acting  on  the  opposite 
side  of  the  boiler,  which  usually  is  sufficient  to  project  the 
boiler  into  the  air  with  considerable  velocity.  As  showing  the 
amount  of  force  which  exists  even  with  small  pressures  we 
would  have  for  each  square  foot  of  the  boiler  with  10  pounds 
pressure  above  the  atmosphere  a  force  of  1440  pounds  per 
square  foot  of  surface,  applied  to  move  it  as  a  projectile.  If 
the  pressure  were  ten  times  as  great  the  force  would  be  ten 
times  greater,  and  the  effect  many  times  worse.  The  disaster 
caused  by  the  explosion  would  depend  largely  upon  the  sud- 
denness with  which  this  force  was  applied  ;  if  it  were  applied 
gradually  no  bad  results  might  follow;  if  applied  instantly  the 
results  might  equal  the  explosion  of  a  large  amount  of  dyna- 
mite. Boilers  sometimes  explode  because  of  defective  mate- 
rial, poor  construction,  or  overheating  of  parts  ;  they  also  some- 
times explode  because  of  defects  in  the  safety-valve  or  in  the 
appliances  for  showing  the  true  level  of  the  water;  but  in  all 
cases  the  immediate  cause  of  the  explosion  is  over-pressure. 
The  causes  which  lead  to  the  formation  of  steam  with  a  pres- 
sure in  excess  of  that  of  the  strength  of  the  boiler  are  vari- 
ous ;  one  of  them  is  the  practice  of  permitting  the  water  in 
the  boiler  to  get  low  and  then  supplying  feed-water,  which 
because  of  the  highly  heated  condition  of  the  surfaces  is  rapidly 
converted  into  steam,  causing  the  pressure  to  become  exces- 
sively high. 

It  is  not  necessary  to  suppose  that  boiler  explosions  are 
caused  by  any  mysterious  force  which  is  suddenly  developed 
in  the  boiler.  On  the  other  hand,  the  amount  of  force  which  is 
stored  in  the  hot  water  and  steam  is  sufficient  to  produce  at  any- 
time  a  terrific  explosion,  provided  the  necessary  opportunity  is 
presented.  Dr.  R.  H.  Thurston  has  computed  the  energy  stored 
in  vari®us  classes  of  boilers  under  the  ordinary  conditions  of 
working,  and  the  following  table  shows  some  of  the  principal 
results  of  that  calculation  and  will  give  some  idea  of  the  enor- 
mous force  stored  in  heated  water  and  steam  : 


SETTINGS  AND   APPLIANCES. 


173 


STORED  ENERGY  OF  STEAM-BOILERS.* 


Type. 

Pressure,  Ibs. 
per  sq.  in. 

\  . 

£°< 

•033 
i 

« 

Total 
Stored  Energy 
Available. 

Energy 
per  Ib.   of 
Boiler. 
Foot-lbs. 

Maximum 
Ht.of 
Proj't'n  of 
Boiler. 
Feet 

Initial 
Velocity. 
Total 

i.  Plain  cylinder.  .  . 
2.  Cornish  cylinder. 
3.  Two-flue  cylind'r 
4.  Plain  tubular.  .  .  . 
5   Locomotive 

IOO 

30 
150 

75 

joe 

10 
60 

35 
60 

C2C 

47,281,898 
58,260,060 
82,949,407 
51,031,521 
54  O44.Q7I 

18,913 
3,43' 
12,243 
5,3/2 
2,786 

18,913 
3,431 
12,243 
5,372 
2  786 

606 
290 
625 

430 

•275 

9.  Scorch  marine.   . 
10.                            .  . 
ii.  Flue  and  return  . 

13.  Water  tube  ...    . 
14        "         " 

125 

125 
125 

75 
75 
30 
30 

IOO 

IOO 

650 

6OO 

425 
300 
350 
2OO 
1  80 
250 
2CQ 

71,284,592 
66,213,717 

65,555,591 
72,734,800 
109,724,732 
92,101,987 
104,272,264 
174,56^,380 
2^0,870,830 

2,851 
3,219 
4,077 
2,687 
2,889 
1,644 
1,862 
5,067 
5,130 

2,851 
3,219 
4,677 
2,687 
2,889 
1,644 
1,862 
5,067 

CT-JQ 

379 
397 
455 
348 
356 
245 
253 
445 
4.50 

15.      "         "     

IOO 

250 

109,624,283 

2,030 

2,030 

323 

"Steam-boiler  Explosions,  in  Theory  and  Practice,"  by  R.  H.  Thurston. 

Considering  the  total  number  of  heating-boilers  in  use  in  the 
United  States  the  number  of  explosions  is  very  small,  so  that 
if  we  suppose  no  improvement  in  construction  over  the  ordi- 
nary methods,  the  risk  which  any  person  would  run  is  very 
slight  ;  and  it  seems  quite  probable  that  if  one  were  to  use  a 
heating-boiler  as  safe  as  the  average  boiler,  the  chances  would  be 
[that  if  he  did  not  die  until  killed  from  this  cause  he  would  live  to- 
be  10,000  years  old.  That  is,  estimating  from  the  total  number 
;of  boilers  in  use  for  heating,  as  compared  with  the  number  of 
explosions  of  such  boilers,  the  chances  are  that  one  per  year 
tin  ten  thousand  would  explode. 

Some  disastrous  explosions  of  heating-boilers  have,  how- 
ever, occurred  in  the  United  States,  of  which  may  be  mentioned 
that  at  the  Central  Park  Hotel,  Hartford,  Feb.  17,  1889,  m 
which  fifteen  people  were  killed  and  the  hotel  entirely  de- 
[stroyed  ;  also  the  boiler  explosion  at  St.  Mary's  Church,  Fort 
Wayne,  Ind.,  in  which  the  church  and  priest's  house  were  nearly 
torn  down,  which  occurred  Jan.  13,  1886;  another  at  Dell 
[Brown's  Hotel,  Eagle  Bridge,  N.  Y.,  Dec.  20,  1888,  in  which 
[several  people  were  injured  and  the  building  badly  wrecked. 
Also  various  other  explosions  doing  less  damage. 

It  would  seem,  from  a  study  of  the  boilers  which  are  in- 
[  jured  by  explosions,  that  no  boiler  is  entirely  free  from  the  dis- 


174 


HEATING   AND    VENTILATING   BUILDINGS. 


astrous  effects  of  an  explosion  when  it  is  badly  managed;  but 
on  the  other  hand  it  also  appears  that  the  sectional  boilers,  or 
boilers  in  which  the  water  occurs  in  small  quantities,  are  subject 
to  injuries  which  are  comparatively  slight  and  generally  easily 
repaired.  So  far  as  the  writer  can  find  from  a  study  of 
all  the  explosions  recorded  in  the  United  States,  the  water- 
tube  boilers,  or  those  with  small  masses  of  water,  are  singu- 
larly exempt  from  disastrous  explosion.  They  are,  however, 
quite  likely  to  have  some  part  broken  away,  in  which  case  the 
pressure  on  the  boiler  is  relieved  quickly  enough  to  avert  a 
serious  explosion.  The  worst  accidents  which  usually  happen 
to  the  sectional  boilers  are  those  due  to  the  burning  out  of  a 
tube  or  some  easily  replaceable  part.  This  results  ordinarily 
in  a  very  severe  leak,  which  can,  however,  be  repaired. 

The  total  number  of  boiler  explosions  for  the  United  States 
for  all  classes  of  boilers  average  about  255  per  year,  and,  as  re- 
ported by  the  Locomotive,  they  have  been  as  follows  for  the 
last  ten  years : 

BOILER  EXPLOSIONS  IN  THE  UNITED  STATES. 


Year. 

Total  No. 
Explo- 
sions. 

Station- 
ary, etc. 

Portable. 

Saw- 
mills. 

Railway 
Locomo- 
tives. 

Steam- 
boats. 

Total 
Killed. 

Total 
Injured.      < 

1884 

152 

48 

18 

56 

15 

15 

254 

26l 

1885 

155 

80 

16 

33 

10 

16 

220 

288 

1886 

185 

88 

16 

45 

22 

14 

254 

3f4 

1887 

198 

67 

2O 

73 

14 

14 

264 

388 

1888 

246 

104 

30 

69 

23 

20 

331 

505 

1889 

1  80 

85 

21 

56 

15 

13 

304 

433 

1890 

226 

94 

16 

75 

25 

16 

244 

35i 

1891 

257 

"5 

35 

68 

22 

17 

263 

371 

1892 

269 

122 

24 

79 

33 

II 

298 

442 

1893 

245 

22O 

151 

1894 

The  following  table  gives  the  total  number  in  Great  Britaii 
for  the  same  time  : 

BOILER  EXPLOSIONS  IN  GREAT  BRITAIN. 


Years. 

1882-83 
1883-84 
1884-85 
1885-86 
1886-87 
1887-88 
1888-80 

Explosions. 

45 
41 
43 
57 
37 
61 
67 

Killed. 

35 
18 
40 
33 
24 
31 
33 

Years. 
1889-90 
1  890-9  1 
1891-92 
1892-93 

Total... 
Ratio.  . 

Explosions. 

77 
72 

88 
72 

..     660.... 

Killed. 
21 
32 
23 
20 

313 

,d82 

SETTINGS  AND   APPLIANCES. 


175 


This  table  would  seem  to  indicate  that  the  explosions  in  this 
country  were  more  disastrous,  so  far  as  taking  life  is  concerned, 
as  in  this  country  two  people  were 
killed  for  about  every  three  ex- 
.plosions,  whereas  in  Germany  and 
Great  Britain  we  have  about  twice 
as  many  explosions  as  deaths.  This 
is  probably  due  to  the  fact  that 
the  statistics  in  this  country  classify 
as  boiler  explosions  only  those  which 
?are  markedly  disastrous,  whereas  in 
France  and  Germany  every  leak  or 
break  which  appears  from  this  cause 
is  recorded  as  an  explosion. 

As  showing  the  disastrous  effects 
often  produced  by  a  boiler  explo- 
sion, the  following  is  abstracted 
from  Thurston's  Manual  of  Steam- 
boilers. 

room   before   the   explosion.     The 
boiler   was   made    of    T5^  iron,  was  3    feet   in    diameter,  and 
was   7   feet  high ;    the   upper   tube-head  was  flush  with  the 


Fig.  170  shows  the  boiler-  THE  BoI1ERF£F^R°E  ExPLOSION. 


FIG.  171. — PATH  TAKEN  BY  THE  BOILER. 

top   of  the  shell,  the   lower  forming   the   crown  of  the  fur- 
nace, which  was  about  2  feet  above  the  grates  and  the  base 


17^  HEATING   AND    VENTILATING   BUILDINGS. 

of  the  shell,  and  was  flanged  upon  the  inner  surface  of 
the  furnace.  There  was  a  safety-plug  in  the  lower  tube- 
head  which  was  not  melted  out.  The  working  pressure  was 
60  pounds  per  square  inch,  and  the  explosion  probably  took 
place  at  or  a  little  below  this  pressure,, 
throwing  the  boiler  through  the  roof  and 
high  over  a  group  of  buildings  and  a  tall; 
tree  close  by,  finally  burying  itself  half 
its  diameter  in  the  frozen  ground.  There 
had  been  a  leak  in  the  lower  head  which 
had  reduced  by  erosion  the  thickness  of 
the  tubes  and  the  lower  head,  so  that  the 
pressure  was  sufficient  to  force  the  lower 

head  down  away  from  the  tubes,  opening  fifty  or  more  holes 
2  inches  in  diameter  from  which  the  fluid  contents  of  the,' 
boiler  issued  at  a  high  velocity,  relieving  the  pressure  belowj 
and  converting  the  whole  boiler  into  a  great  rocket  weighing'; 
about  2000  pounds. 

103.  Explosions    of    Hot-water    Heaters. — While   hot-; 
water  heaters  provided  with  an  open  expansion-tank  are  to  a; 
great  extent  free   from  the   dangers  of  explosions,  still  it  is 
quite  possible  that  extreme  carelessness  in  erection,  the  freez-| 
ing  up  of  connections  to    expansion-tank,  or  other  mishaps, 
might  render  the  apparatus  fully  as  dangerous  as  the  steam- 
boiler  under  its  most  unfavorable  conditions.     Some  very  disi 
astrous  explosions  have  occurred  of  hot-water  heating  plants.- 
when  operated  under  the  Perkins  or  high-pressure  system,  and.: 
it  seems  quite  probable  that  such  a  system,  even  under  the^ 
most  favorable  conditions,  is  more  dangerous  than  the  steam* 
heating   system.     The    hot-water   heating   system    should    be* 
constructed   so  that   the   connection  between  the   expansion* 
tank   and   heater  cannot   by  any  possible    means  be   closed! 
The  placing  of  a  valve  in  this  connection  was  the  cause  of  I 
very  disastrous   explosion  in  a  residence   in  New  York  CitJJ 
quite   recently,   and  emphasizes  the   necessity  for  caution  in 
this  respect. 

104.  Prevention  of  Boiler  Explosions. —  Boiler  explo-j 
sions  are  probably  preventable  in  every  single  case  by  using, 
first,  boilers  properly  designed,  and   constructed   of  excellent! 


SETTINGS  AND   APPLIANCES.  177 

material  and  with  good  workmanship  ;  and  second,  by  seeing 
that  all  appliances,  as  safety-valves,  blow-off  cocks,  feeding 
apparatus,  etc.,  are  in  excellent  order ;  and  third,  by  providing 
skilled  and  intelligent  attendance. 

Disastrous  results  are  usually  almost  entirely  prevented  by 
the  use  of  sectional  boilers,  and  for  heating  purposes  there 
!are  at  the  present  time  comparatively  few  of  any  other  kind 
in  use. 

As  a  rule  heating-boilers,  especially  those  of  small  sizes, 
are  not  under  close  supervision,  but  are  attended  to  and 
visited  only  at  comparatively  long  intervals.  For  this  reason 
automatic  appliances  for  feeding  the  boiler  and  for  regulating 
the  pressure,  opening  and  closing  the  dampers,  are  usually 
supplied  ;  hence  the  person  erecting  the  plant  should  exercise 
;the  utmost  care  to  see  that  such  appliances  are  in  excellent 
order  and  of  such  character  as  are  likely  to  prove  durable  and 
reliable.  While  it  is  quite  certain  from  our  statistics  that  not 
one  boiler  out  of  ten  thousand  is  likely  to  explode  per  year, 
yet  nevertheless  the  contractor  should  always  bear  in  mind 
that  a  steam-boiler  is  in  every  case  a  magazine  of  stored 
energy,  and  if  badly  constructed,  poorly  erected,  or  carelessly 
managed  may  do  an  immense  amount  of  damage. 


CHAPTER    IX. 
VARIOUS   SYSTEMS   OF   PIPING. 

105.  Systems   employed  in  Steam-heating. — There  are 
two  systems  of  heating,  in  the  first  of  which,  known  as  the 
Gravity  Circulating  System,  the  water  of  condensation  from 
the  various  radiators  flows  by  its  own  weight  into  the  boiler  at 
a  point  below  the  water  line  ;  in  the  second  the  water  of  con- 
densation does  not  flow  directly  into  the  boiler,  but  is  returned 
by  some  special  machinery  or,  in  some  cases,  wasted.     The 
second  system  is  often  called  the  High-pressure  System,  be- 
cause steam  of  any  pressure  can  be  produced  in  the  boiler,  a  por- 
tion of  which  may  be  employed  in  operating  engines,  elevators, 
etc.     It  is  very  seldom,  however,  that  this  high-pressure  steam 
is  used  in  radiators,  low-pressure  steam  being  obtained  directly 
from  the  boiler  by  throttling  or  passing  through  a  reducing- 
valve,  or,  in  some  instances,  indirectly  by  using  the  exhaust- 
steam  from  engines  or  pumps. 

In  this  chapter  we  shall  discuss  only  the  systems  of  piping 
used  with  gravity  circulating  systems  of  heating,  reserving 
for  a  later  chapter  a  description  of  the  methods  employed  in 
the  other  system  of  heating,  although  there  is  in  the  arrange- 
ment of  pipe  lines  very  little  which  pertains  to  either  system 
exclusively. 

106.  Definitions    of  Terms    used. — Certain  terms  have 
been  adopted  which  are  always  used  to  describe  definite  parts 
in  a  system  of  piping,  as  follows  : 

The  main  or  distributing  pipe  is  the  pipe  leaving  the  boiler 
or  heater  and  conveying  the  heated  products  to  the  radiating 
surfaces.  In  steam-heating  this  is  termed  the  main  steam-pipe, 
and  in  hot-water  heating  the  totain  flow-pipe.  It  maybe  car- 
ried from  the  boiler  without  branches  to  the  top  of  the  build- 

178 


VARIOUS  SYSTEMS   OF  PIPING.  1/9 

ing  (Fig.  173),  where  the  distributing-pipes  are  taken  off,  or  it 

may  run  in  a  horizontal  or  vertical  direction  from  the  heater, 

and  branch  pipes  taken  off  as  required.     The  pipes  in  which 

i  the  flow  takes  place  from  the  radiating   surface  toward  the 

boiler  are  called  return-pipes.     The  pipes  which  extend  in  a 

;  vertical  direction  are  termed  risers;  when  the  flow  in  these 

pipes  is  downward  they  are  called  return-risers. 

A  relief  or  drip  is  a  small  pipe  run  from  a  steam-main,  so 
as  to  convey  any  water  of  condensation  to  the  return ;  it  must 
be  employed  at  all  points  where  water  is  likely  to  gather. 
For  illustration  of  use  see  Fig.  176. 

Pitch  is  the  inclination  given  to  any  pipe  when  running  in 
;  nearly  a  horizontal  direction.  In  general  the  inclination  or 
pitch  of  a  supply-pipe  should,  in  steam-heating,  be  downward 
from  the  boiler,  and  arranged  so  that  the  water  of  condensa- 
tion will  move  in  the  same  direction  as  the  current  of  steam. 
In  hot-water  heating  the  pitch  should  be  upward  from  the 
boiler.  In  all  return-pipes  the  inclination  should  be  down- 
rward,  toward  the  heater  or  boiler. 

A  relay  is  a  term  sometimes  used  to  describe  a  sudden 
change  of  alignment,  or  "  jumping  up,"  of  a  horizontal  pipe. 
This  is  often  necessary  in  a  long  line  of  piping  to  keep  the  pipe 
near  the  ceiling  and  preserve  the  necessary  pitch.  At  such 
points  a  drip  or  relief  must  permit  water  of  condensation  to 
flow  into  the  return. 

Water-line  is  a  term  used  to  denote  the  height  at  which  the 
:  water  will  stand  in  the  return-pipes.  It  is  usually  very  nearly 
the  same  as  the  level  of  the  water  in  the  boiler,  being  higher 
only  in  case  there  is  considerable  reduction  in  pressure  due  to 
friction.  In  heating  with  high-pressure  steam  it  is  desirable 
to  have  all  the  relief-pipes  discharge  into  a  return  filled  with 
water,  so  that  circulation  of  steam  shall  be  continuously  in 
one  direction ;  this  is  of  less  importance  with  low-pressure 
steam,  provided  the  water  which  gathers  in  returns  can  move 
freely  and  quickly  to. the  boiler. 

The  term  siphon  is  applied  to  a  bend  below  the  horizontal ; 
it  is  sometimes  used  in  the  main  return  to  hold  water  at  a  dif- 
ferent level  from  that  in  the  boiler.  This  is  done  by  admitting 
steam  to  the  top  part  of  the  bend  on  the  boiler  side  by  a  relief 


ISO  HEATING   AND    VENTILATING   BUILDINGS, 

from  the  main  steam-pipe.  It  is  similar  to  the  siphon-trap, 
Fig.  159,  Article  98.  If  the  relief  were  not  connected  to  the 
top  of  the  bend  the  water  would  pass  over  by  suction  into 
the  boiler. 

Steam-traps  are  vessels  designed  with  valves  which  open 
automatically  so  as  to  preserve  the  water-level  in  the  re- 
turns at  any  desired  point.  Various  kinds  are  described  in 
Chap.  VIII,  Article  98. 

Water-hammer  is  a  term  applied  to  a  very  severe  concus- 
sion which  often  occurs  in  steam-heating  pipes.  It  is  caused 
by  water  accumulating  to  such  an  extent  as  to  condense  some 
of  the  steam  in  the  pipe,  thus  forming  a  vacuum  which  is  filled 
by  a  very  violent  rush  of  steam  and  water.  The  water  strikes  the 
side  of  the  radiators  or  pipes  with  great  force,  and  often  so  as 
to  produce  considerable  damage.  In  general  a  water-hammer 
may  be  prevented  by  arranging  the  piping  in  such  a  manner 
that  the  water  of  condensation  will  immediately  drain  out  of 
the  radiator  or  pipes. 

A  bend  in  the  return  of  a  steam-  or  water-heating  system, 
when  convex  upward,  will  frequently  accumulate  air  to  such 
an  extent  as  to  prevent  circulation  in  the  system.  This  is 
designated  as  an  air-trap.  When  bends  of  this  character  must 
be  used  a  small  pipe  for  the  escape  of  the  air  should  be  con- 
nected with  the  highest  portion  of  the  bend  and  led  to  some 
pipe  which  will  freely  discharge  the  entrapped  air. 

An  air-valve  is  not  ordinarily  to  be  recommended  for  such 
situations. 

107.  Systems  of  Piping. — The  systems  of  piping  ordinar- 
ily employed  provide  for  either  a  complete  or  a  partial  circulat- 
ing system,  each  consisting  of  main  and  distributing  pipes  and 
returns.  Several  systems  of  piping  are  in  common  use,  of 
which  we  may  mention  : 

First,  the  complete-circuit  system,  often  called  the  ojie-pipe 
system,  in  which  the  main  pipe  is  led  directly  to  the  highest 
part  of  the  building ;  from  thence  distributing-pipes  are  run  to 
the  various  return-risers,  which  in  turn  connect  with  the  radiat- 
ing surface  and  discharge  in  the  main  return.  The  supply  for 
the  radiating  surface  is  all  taken  from  the  return-risers,  and  in 


I' A  RIO  US  SYSTEMS   OF  PIPING. 


181 


some  cases  the  entire  downward  circulation  passes  through  the 
radiating  system. 

This  system  was  employed  by  Perkins  in  his  method  of  high- 
pressure    hot-water  heating,  and    is  mentioned    by  Peclet  as 


in  use  in  France  in  1830.  In  this  country  it  seems  to  have  been 
introduced  into  use  by  J.  H.  Mills,  and  is  often  spoken  of  as 
the  Mills  system  of  piping.  The  system  is  equally  well  adapted 
for  either  steam  or  hot-water  heating,  and  on  the  score  of  posi- 
tiveness  of  circulation  and  ease  of  construction  is  no  doubt  to 


182 


HEATING   AND    VENTILATING    BUILDINGS. 


be  commended  as  superior  to  all  others.  It  is  principally  ob- 
jectionable because  the  horizontal  distribution-pipes  have  to  be 
run  in  the  top  story  of  the  building  instead  of  the  basement, 
which  may  or  may  not  be  of  serious  importance. 


Second,  a  partial-circuit  system,  in  which  the  main  flow-pipe 
rises  to  the  highest  part  of  the  basement  by  one  or  more 
branches,  from  whence  the  distributing-pipes  run  at  a  slight 
incline,  often  nearly  around  the  basement,  and  finally  connect 
with  the  boiler  below  the  water-line.  The  radiators  are  con- 


VARIOUS  SYSTEMS   OF  PIPING. 


185 


nected  by  risers  which  carry  both  flow  and  return  from  and  to 
the  distributing  pipes,  as  shown  in  elevation  in  Fig.  174  and  in 
plan  in  Fig.  175.  This  method  of  piping  is  employed  exten- 
sively for  steam-heating,  and  is  perhaps  less  open  to  objection 
than  any  other. 


Third,  a  system  of  circulation  in  which  each  radiator  is  pro- 
vided with  separate  flow-  and  return-pipes  (Fig.  176).  In  this 
case  the  riser  and  distributing  pipes  are  run  as  before,  but  are 
connected  to  the  return  by  a  drip-pipe ;  the  return  is  located 


1 84 


HEATING   AND    VENTILAJ^ING   BUILDINGS. 


below  the  water-line  of  the  boiler.  The  supply-riser  from  each 
radiator  is  taken  from  the  main  flow-pipe,  and  the  return-riser 
is  connected  to  the  main  return  below  the  water-level.  In  case 
two  connections  are  made  to  a  radiator,  one  for  supply  and  the 
other  for  the  return,  it  is  quite  important  that  the  connection 


of  the  return-riser  to  the  main  return  be  made  below  the  water 
level  of  the  boiler,  in  order  to  prevent  steam  flowing  from  two 
directions  to  the  radiator.  Such  a  condition  is  certain  to  cause 


VARIOUS  SYSTEMS   OF  PIPING.  1 85 

fater-hammer,  as  the  radiator  will  retain  water  of  condensa- 

ion. 

Various  modifications  of  this  third  system  have  been  used 
from  time  to  time  with  greater  or  less  success.     For  instance, 

;ach  radiator  has  in  some  cases  been  connected  to  a  separate 
>w  and  return  riser,  and  in  other  cases  simply  to  a  separate 

'turn  riser.     These  modifications  are  unimportant  and  hardly 

'orthy  of  notice. 

108.  Methods  of  Piping  Used  in  Hot-water  Heating.— 
A  system  of  hot-water  heating  should  present  a  perfect  system 
of  circulation  from  the  heater  to  the  radiating  surface  and  thence 
back  to  the  heater  through  the  returns;  an  expansion-tank 
being  provided,  as  explained,  to  prevent  excessive  pressure  due 
to  the  heating  and  the  consequent  expansion  of  the  water.  The 
direct-circuit  system,  as  described  for  steam-heating,  Fig.  173, 
is  well  adapted  for  hot-water  heating,  and  has  been  used  to  a 
limited  extent.  When  this  system  is  employed  for  hot-water 
heating  two  connections  are  usually  taken  off  from  the  return 
riser  at  different  levels  for  each  radiator,  as  shown  in  Fig.  103, 
page  114;  although  in  some  cases  a  single  connection  is  made 
and  a  radiator  of  ordinary  form  employed,  otherwise  the 
method  of  piping  is  exactly  similar  to  that  described  for  steam- 
heating. 

The  system  of  piping  ordinarily  employed  for  hot-water 
heating  is  illustrated  in  Fig.  177.  In  this  system  the  mains 
and  distributing  pipe  have  an  inclination  upward  from  the 
heater;  the  returns  are  parallel  to  the  main  and  have  an  inclina- 
tion downward  toward  the  heater,  connecting  at  its  lowest  part. 
The  flow-pipes  are  taken  from  the  top  of  the  main  and  supply 
one  or  more  radiators.  The  return-risers  are  connected  with 
the  return-pipe  in  a  similar  manner.  In  this  system  great  care 
must  be  taken  to  produce  nearly  equal  resistance  to  flow  in  all 
the  branches  leading  to  the  different  radiators.  It  will  be  found 
that  invariably  the  principal  current  of  heated  water  will  take 
the  path  of  least  resistance,  and  that  a  small  obstruction,  any 
irregularity  in  piping,  etc.,  is  sufficient  to  make  very  great  dif- 
ferences in  the  amount  of  heat  received  in  different  parts  of 
the  same  system.  For  instance,  two  branch  pipes  connected 
at  opposite  ends  of  a  tee,  which  itself  is  connected  by  a  centre 


1 86 


HEATING   AND    VENTILATING   BUILDINGS. 


opening  to  a  riser,  are  almost  certain  to  have  an  irregular  and 
uncertain  circulation. 


The  method  of  piping  generally  adopted  for  the  closed  or 
high-pressure  system  is  that  of  the  complete-circuit  or  one-pipe 
system,  as  illustrated  in  Fig.  173.  .This  system  when  now 
employed  is  used  only  for  moderately  low  pressures,  and  a 
safety-valve  is  provided  on  the  expansion-tank  to  prevent 
excessive  pressure.  In  this  system,  or,  in  fact,  in  any  of  the 
systems  for  hot-water  heating,  the  level  of  the  return-pipe  can 


VARIOUS  SYSTEMS   OF  PIPING. 


I87 


be  carried  below  that  of  the  heater  without  bad  results.     The 
lethod  of  applying  this  system  is  shown  in  Fig.  178,  which  is 


> 
n 

*i 


^ 

w  _ 

-•  ^r 

w  o 

*  5 


H  ^ 

>   G 

g." 


2  > 

PJ   -: 


B  5 


similar  in  many  respects  to  that  used  in  the  Baker  system  of 
ir-heating. 

The  expansion-tank  must  in  every  case  be  connected  to  a 
ine  of   piping  which  cannot   by  any  possible  means  be  shut 
off  from  the  boiler.     It  does  not  seem  to  be  a  matter  of  im- 
portance whether  it  is  connected  with  the  main  flow  or  with 


1 88  HEATING  AND    VENTILATING   BUILDINGS. 

the  return.  The  form  of  expansion-tank  and  the  different 
kinds  of  fittings  have  been  described  in  Art.  93,  page  158. 
'•"'""Single-pipe  systems  for  hot-water  heating  have  been  used  to 
some  extent.  In  this  case  there  is  a  gradual  flow  of  the  heated 
water  to  the  top,  and  the  consequent  settlement  of  the  colder 
water  to  the  bottom.  The  form  of  piping  would  be  essen- 
tially the  same  as  that  shown  in  Fig.  173  or  174.  The  writer 
erected  such  a  system  at  one  time  as  an  experiment,  and  found 
that  it  worked  well  after  the  water  had  once  become  heated. 
Where,  there  is  no  objection  to  a  system  which  heats  slowly, 
this  would  probably  do  well  on  a  small  scale,  but  could  not  be 
recommended  for  an  extensive  job. 

109.  Combination  Systems  of  Heating. — Several  methods 
have  been  devised  for  using  the  same  system  of  piping  alter- 
nately for  steam  or  hot  water  as  the  demand  for  higher  or 
lower  temperature  might  change.  The  object  of  this  is  to 
secure  the  advantages  which  pertain  to  the  hot-water  system 
of  heating  for  moderate  temperature  and  to  steam-heating 
for  extremely  cold  weather.  As  less  radiating  surface  is  re- 
quired for  steam-heating,  there  is  the  advantage  due  to  reduc- 
tion in  first  cost.  This  may  be  of  considerable  moment,  since  \ 
a  heating  system  must  be  designed  of  such  dimensions  as  to  be  ; 
satisfactory  in  the  coldest  weather,  and  this  involves  the  ex- 
penditure of  a  considerable  amount  for  surfaces  which  are 
needed  only  at  rare  intervals. 

The  combination  system  of  hot-water  and  steam  heating 
must  require,  first,  a  heater  or  boiler  which  will  answer  for 
either  purpose  ;  second,  the  construction  of  a  system  of  piping 
which  will  permit  the  circulation  of  either  steam  or  hot  water ; 
third,  the  use  of  radiators  which  are  adapted  to  both  kinds  of ) 
heating. 

These  requirements  will  be  met  in  the  best  manner  by  using 
a  steam-boiler  provided  with  all  the  fittings  required  for  steam- 
heating,  but  so  arranged  that   the  damper   regulator  may  be 
closed  off  from  the  heater  by  means  of  valves  when  the  system 
is  needed   for  use   in  hot-water  heating.     The  addition  of  an  j 
expansion-tank  is   required,  which  must   be  arranged  so  that  j 
it  can   be  closed  off  when   the  system  is  required  for  steam- 
heating. 


VARIOUS   SYSTEMS   OF  PIPING.  189 

Of  the  different  systems  of  piping,  that  designated  as  the 
complete-circuit  or  one-pipe  system  (Fig.  173)  is  the  only  one 
which  is  equally  well  adapted  for  both  hot  water  and  steam.  In 
case  that  system  cannot  be  conveniently  installed,  the  one 
shown  in  Fig.  177  for  hot  water  will  be  found  to  give  fairly 
good  results,  it  being  objectionable  in  steam-heating  only 
because  of  the  fact  that  the  condensation  jn  the  main  pipe 
flows  against  the  current.  The  radiators  and  connecting  pipes 
should  be  of  the  form  required  for  hot-water  heating,  but  the 
proportions  and  dimensions  the  same  as  for  steam-heating. 

While  this  system  has  many  advantages  in  the  way  of  cost 
over  the  complete  hot-water  system,  yet  the  labor  of  changing 
from  steam  to  hot  water  will  in  some  cases  be  troublesome, 
and  should  the  connections  to  the  expansion-tank  not  be 
opened,  serious  results  would  certainly  follow. 

A  combination  hot-air  furnace  and  hot-water  system  has 
been  employed  to  considerable  extent.  In  such  a  case  the 
water-heating  surface  is  obtained  by  inserting  a  coil  of  pipe  or 
suitable  vessel  into  the  hot-air  furnace,  and  certain  rooms  and 
portions  of  the  house  are  warmed  by  the  heated  air  directly 
from  the  furnace,  while  other  parts  are  heated  by  the  circula- 
tion of  hot  water. 

This  system  is  an  admirable  one  from  every  point  of  con- 
sideration, theoretically ;  but  practically  it  is  a  very  difficult 
one  to  design  and  construct  in  such  a  manner  that  the  supply 
of  heat  to  the  different  rooms  shall  be  positive  and  well  dis- 
tributed. Fig.  179  shows  the  arrangement  of  such  a  system.* 
In  this  case  the  hot-air  furnace  supplies  heat  to  the  lower  floors 
and  the  hot-water  circulating  system  to  the  upper  floors. 

Any  system  of  piping  suitable  for  hot-water  heating  can  be 
employed  for  this  purpose  :  the  one  shown  is  that  of  the  com- 
plete-circuit or  one-pipe  system,  the  heated  water  being  taken 
directly  to  the  top  of  the  building  and  all  radiating  surface 
supplied  by  the  descending  current.  As  the  writer  knows 
from  experience,  it  is  very  difficult  indeed  to  proportion  the 
heating  surface  in  the  furnace  and  the  radiating  surface  in  the 
room  so  as  to  give  in  all  cases  satisfactory  results  without  an 

*  An  admirable  series  of  articles  were  written  on  this  subject  by  J.  W.  Hughes, 
and  appeared  in  Metal  Worker,  February'  1895. 


HEATING   AND    VENTILATING   BUILDINGS. 


irregular  and  uncertain  distribution  of  heat.  It  will  generally 
be  found  that  the  fire  maintained  in  a  hot-air  furnace  is  much 
more  intense  than  that  in  a  steam  or  hot-water  heater ;  and 
further,  the  heating  surface  which  is  usually  employed  is  sub- 
jected to  the  full  heat  of  the  fire,  consequently  a  smaller 
amount  of  heating  in  proportion  to  radiating  surface  must  be 


FIG.  179.— COMBINATION  SYSTEM.  HOT-AIR  FURNACE  AND  HOT  WATER. 

-employed.  Whereas  in  the  ordinary  hot-water  heater  one  foot 
of  heating  surface  supplies  from  8  to  10  of  radiating  surface,  in 
this  system  I  foot  of  heating  surface  will  supply  25  to  35  feet 
qf  radiating  surface  in  coal-burning  furnaces  and  50  to  75  in 
wood-burning  furnaces. 

Similar  combination  systems  of  hot  air  and  steam  are  also 
used,  but  in  such  cases  the  heater  must  be  very  much  like  a 
steam-boiler,  and  possess  all  its  appliances  and  also  storage 
capacity  for  steam.  In  the  case  of  the  hot-water  and  hot-air 
system  the  heater  is  substantially  a  hot-air  furnace,  to  which  is 
added  a  coil  of  pipe  or  vessel  of  suitable  form,  which  serves  as 
the  heating  surface  for  the  hot  water,  so  that  the  change  in 
construction  is  very  slight ;  but  for  steam-heating  the  change 
of  construction  must  be  more  marked,  and  is  likely  to  be  more 
expensive  and  complicated. 


VARIOUS  SYSTEMS   OF  PIPING. 


no.  Pipe  Connections,  Steam-heating  Systems. — The 

manner  in  which  branches  are  taken  off  may  have  great  effect 
on  the  results  obtained  in  any  heating  system,  since  any  in- 
crease in  friction  in  any  part  of  the  system  will  cause  the 
flow  to  be  sluggish  in  that  portion,  and  require  more  press- 
ure to  induce  circulation.  The  size  of  pipes  required  in  order 
that  resistances  may  not  exceed  a  certain  amount  are  given  in 
the  next  chapter;  but  it  should  be  noted  that  bad  workman- 
ship may  defeat  the  operation  of  a  steam-heating  plant  having 
the  best  proportions  possible,  and  that  great  care  is  needed,  (i) 
to  secure  the  alignment  of  every  part,  (2)  the  absence  of  air- 
traps  or  any  obstructions  whatever  which  would  reduce  the 
circulation  or  make  it  irregular  or  uncertain.  Some  details 
which  are  to  be  considered  rather  as  suggestions  than  as  formal 
directions  are  given. 

In  general,  pipe  connections  should  be  made  so  as  to  afford 
'as  little   resistance  as  possible  to  the  flow  of   steam,  and  in 
such    a   manner    as    not    to    interfere    with   the  expansion  of 
$he  main  pipes.     The  line  of  piping  should  present  the  freest 
^possible    channels  of   circulation   for   the  steam   as   it  leaves 
the  boiler  and  for  the  water  of    condensation    as    it  returns. 
JTne  expansion,  which  is  not 
^essentially    different    from    if 
inches    for    each    100    feet    in 
length,    can    usually   be    well 
provided    for   by   the    use   of 
two  or  more   right-angled   el- 
bows   substantially  as   shown 
tin  Fig.  1 80.     No  general  rule 
can   be  laid  down  for  all  cir- 
cumstances    and     conditions. 
The  following  examples   and 
illustrations  from  Heating  and 
Ventilation  show  the  methods 
of  piping  commonly  employed 
in  setting  steam-radiators  with  FIG.  180.— CONNECTION  TO  RADIATOR 
one-pipe  connections.  Fig.  180  FROM  STEAM  MAIN- 

illustrates  the  method  where  the  radiator  is  set  close  to  the 
main  and  no  special  drip  is  required. 


IQ2  HEATING   AND    VENTILATING   BUILDINGS. 

The  method  often  employed  in  connecting  a  riser  to  a 
horizontal  steam  main  and  running  a  special  drip-pipe  for  con- 
densed water  to  the  return  main  is  shown  in  Fig.  181. 


RETURN 
MAIN 


FIG.  181. — CONNECTION  TO  RISER  FROM  MAIN  AND  RETURN. 

The  method  often  employed  in  connecting  radiators  to 
risers  is  shown  in  the  upper  portion  of  Fig.  182.  The  lower 
portion  illustrates  an  essentially  different  method  from  that! 
shown  in  Fig.  181  of  connecting  the  riser  to  the  main,  and  the 
drip-pipe  to  the  return.  This  method,  however,  does  not  allow 
for  expansion  of  the  steam  main ;  hence  this  must  be  provided 
for  in  some  other  portion  of  its  length. 

The  area  of  the  main  pipe  must  in  every  case  be  equivalent 
in  carrying  capacity  to  that  of  all  the  branches  taken  off ;  it 
consequently  may  be  reduced  as  the  distance  from  the  heater 
becomes  greater  and   as  more  branches  are  supplied.     Table 
XVI.,   Appendix,  gives   the   equivalent  capacity  of    pipes  of 
different  diameters,  and  can  be  used  in  determining  the  rela- 
tive number  of  branches  of  a  given  size,  and  also  the  reduction;! 
in  pipe  area  which  may  be  made  after  a  certain  number  of1 
branches    have  been  connected.     It  will,  however,   in  general^ 
be  found,  except  when  large  pipes  are  used,  less  expensive  to^ 
run  the  main  full  size  than  to  use  reducing  fittings. 


VARIOUS   SYSTEMS   OF  PIPING. 


I93 


in.   Pipe  Connections,  Hot-water  Heating  Systems.— 

If  the  system  of  circulation  adopted  is  the  complete-circuit 
system,  as  in  Fig.  173,  in  which  the  heating  main  is  first  taken 
directly  to  the  top  of  the  building  and  thence  run  horizontally 


FIG.  182.— CONNECTION  OF  RADIATOR  TO  RISER. 

to  the  various  lines  of  return  risers,  the  system  of  construction 
would  be  essentially  the  same  as  that  described  for  a  steam- 
heating  plant.  The  main  riser  should  connect  into  a  drum, 
from  the  top  of  which  the  distributing-pipes  leading  to  the 
return  risers  are  taken.  The  size  of  the  distributing-pipes 
should  be  proportional  to  the  amount  of  radiating  surface, 
and  the  various  distributing-pipes  should  be  arranged  so  that 
the  resistance  in  each  will  be  substantially  equal.  The  flow 
connection  for  each  radiator  should  be  taken  off  at  a  point 
coout  level  with  the  top  of  the  radiator,  as  in  Fig.  103, 


IQ4  HEATING   AND    VENTILATING   BUILDINGS. 

page  1 14,  and  the  return  should  enter  the  same  pipe  at  a  point 
below  the  radiator.  A  valve  affording  as  little  resistance  as^ 
possible  is  to  be  put  in  each  connection.  Hot-water  heating 
systems  have  been  erected  in  which  the  radiators  are  joined  to 
the  riser  by  one  connection  only  ;  and  while  this  system  seems 
to  be  somewhat  slower  in  heating  than  that  with  two  connec- 
tions, it  is  otherwise  quite  satisfactory. 

In  the  system  commonly  employed  the  main  and  distribut-1 
ing  pipes  are  erected  in  the  basement,  as  shown  in  Fig.  177. 
An  offset  from  the  main  to  the  foot  of  the  riser  has  usually  to| 
be  made,  which  should  be  done  as  from  the  steam  main  in  Fig. 
1 80,  and  in  such  a  manner  as  to  take  the  flow  from  the  upper 
part  of  the  pipe ;  such  a  connection  is  also  shown  in   No.  3!] 
Fig.  183.     The  connection  to  the  main  return  may  be  made  on 


.   j 
i 

h  i 

FIG.  183. — CONNECTIONS  TO  MAINS,  HOT-WATER  HEATING. 
the  side  or  at  the  top,  as  convenient.     In  some  instances  a  tee  j 
turned  at  an  angle  and   a  45-degree  elbow  can  be  used  with 
good   results,  as  shown  at  No.  2,  Fig.  183.     The  method  offj 
connecting  shown  at  No.  I  should  only  be  employed  in  case  f 
the  room  is  not  sufficiently  high  for  connections,  as  shown  at 
No.  3,  as  its   use   is  attended  with  doubtful  success  in  many 
cases. 

In  taking  off  branches  from  the  top  of  a  riser  a  tee  should  | 
seldom  or  never  be  employed,  since  it  will  be  found  that  ifiii 
for  any  reason  the  current  becomes  established  in  one  directioiil 
it  will  be  very  difficult  to  induce  it  to  flow  in  the  other|| 
When  branches  running  in  opposite  directions  have  to  be  takefl|| 
from  the  main  riser,  long-radius  tees,  as  shown  in  Fig.  5211 
page  95,  should  be  employed;  but  unless  the  riser  is  long  it  wiUpjj 
in  general  be  better  to  erect  a  separate  line  for  each  branch|| 
Precautions  should  be  taken  in  every  case  that  the  junction  ofjili 
two  currents  shall  not  exert  an  opposing  force  which  will  imll 
pede  the  circulation. 


VARIOUS  SYSTEMS    OF  PIPING. 


195 


The  connections  to  radiators^  for  this  system  need  to  be 
made  in  such  a  way  that  the  horizontal  branches  which  are 
taken  off  from  the  risers  will  receive  a  strong  current  of 
water.  There  is  a  tendency  for  water  to  flow  directly  in  the 
line  of  motion,  and  to  the  highest  radiators  in  the  system. 
^This  renders  it  necessary  to  increase  the  resistance  in  the 
•riser  beyond  the  branch  a  greater  or  less  amount  in  order  to 
induce  circulation  into  the  side  connections.  This  may  be 
jdone  in  several  ways,  as  shown  in  Fig.  184:  (i)  by  connecting 


FIG.  184. — CONNECTION  TO  RADIATORS,   HOT-WATER   HEATING. 

the  radiator  to  an  elbow  placed  on  the  main  pipe  and  con- 
Etinuing  the  main  pipe  from  the  side  opening  of  a  tee  or  Y, 
las  shown  at  A  and  B ;  or  (2)  by  using  a  reducing  fitting,  as 
[shown  at  C,  and  continuing  the  riser  with  a  reduced  diameter. 
The  return  connections  can  be  made  in  a  similar  manner,  but 
tthey  will  in  every  case  work  well  if  the  return  riser  be  run  in 
a  direct  line  and  the  connection  be  made  into  the  side  opening 
of  a  Y. 

112.  Position  of  Valves  in  Pipes. — If  a  valve  has  to  be  used 
on  a  horizontal  pipe  it  should  be  located  so  as  to  afford  the 
least  possible  obstruction  to  the  flow  of  water  in  the  required 
direction.  If  a  globe  valve  be  used  with  the  stem  set  vertically, 
Fig.  185,  it  will  form  an  obstruction  sufficient  to  fill  the  pipe 
very  nearly  full  of  water ;  if  the  stem  be  placed  in  a  horizontal 
direction  the  flow  of  water  will  be  less  impeded.  Globe  valves 
form  a  great  obstruction  to  the  flow  in  water-heating  pipes,  and 
under  no  circumstances  should  they  be  used  for  that  work.  In 
the  case  of  steam-heating  they  are  less  objectionable,  provided 
they  are  located  in  such  a  manner  as  to  permit  free  drainage 


196 


HEATING   AND    VENTILATING   BUILDINGS. 


of  the  pipes.     In  general,  angle  or  gate  valves  can  be  used, 
however,  in  every  place  with  better  satisfaction. 

For  hot-water  heating  special  valves  have  been  designed, 


FIG.   185. — ILLUSTRATION  OF  WATER  HELD  BY  GLOBE  VALVE. 


which  when  open  offer  no  special  impediment  to  the  flow,  and 
which  close  sufficiently  tight  to  prevent  circulation,  although 
not  sufficient  to  prevent  leaks.  See  page  88. 

113.  Piping  for  Indirect  Heaters. — Indirect  radiators  have 
been    described    and   methods   of  setting  them   illustrated  in 

Article  69,  page  116. 
These  radiators  are  gen- 
erally set  in  a  case  or  box 
which  is  suspended  from 
the  basement  ceiling  and 
made  of  matched  boards 
lined  with  tin,  Fig.  186. 
The  sides  of  the  casing 
should  be  removable  for 
repair  of  the  radiator. 
The  system  of  pipes 
which  supply  the  indirect 
radiators  are  generally 
most  conveniently  erect- 
ed, like  those  shown  in  Fig.  175  or  177  for  steam-heating,  and 
like  that  shown  in  Fig.  179  for  hot-water  heating.  The  heater 
should  be  located  above  the  water-line  of  the  boiler  a  sufficient 
distance  to  afford  ready  means  of  draining  off  the  water  of  con- 
densation. In  case  this  is  impossible,  a  style  of  radiator  should 


FIG.  1 86. — INDIRECT  SURFACE. 


VARIOUS  SYSTEMS   OF  PIPING.  197 

be  adopted  which  can  be  heated  by  water  circulation.  An 
automatic  air-valve  should  be  connected  to  the  heater,  and  every 
means  should  be  taken  to  obtain  perfect  circulation  to  and  from 
the  boiler.  The  chamber  which  surrounds  the  indirect  surface 
is  to  be  supplied  with  air  from  the  outside  by  a  properly 
constructed  flue.  The  air  passes  up  through  or  over  the 
heater  and  into  the  rooms  by  means  of  special  flues,  the  sizes 
of  which  are  given  in  Chapter  X. 

114.  Comparisons  of  Pipe  Systems. — As  to  the  best  sys- 
tem of  piping  to  be  adopted  little  can  be  said  in  a  general  way- 
The  circuit-system,  Fig.  173,  no  doubt  gives  the  freest  circula- 
tion and  is  applicable  to  either  hot-water  or  steam  heating.     In 
some  respects  it  is  simpler  to  construct,  and   it   seems  quite 
probable  that  small  errors  of  alignment,  minute   obstructions, 
and  error  in  proportioning  the   pipes  would  not  be  so  fatal  to 
the  perfect   operation   of   this   system   as  of   the    others.      It 
requires,  however,  that  distributing  pipes  be  placed  in  the  top 
story  of  a  building,  and  this  in  many  cases  will  be  so  objection- 
able that  it  cannot  be  used.     Regarding  other  systems  there 
is  little  to  be  said.     For  steam-heating  there  seems  to  be  little 
or  no  use  in  making  more  than  one  connection  to  any  radiator  I 
and  this  practice,  which  is  now  common,  will  I  think  become 
universal. 

115.  Systems  of  Piping  where  Steam  does  not  Return 
to  the  Boiler. — For  such  systems  the  method  of  piping  and  of 
making   connections   would   be    in    every  case    essentially  as 
described  ;  and  usually  this  can  be  done  with  less  care  because 
of  the  fact  of  greater  difference  of  pressure  between  the  supply 
and  the  return.     Such  systems  are  not  often  employed  except 
in  connection  with  use  of  exhaust  steam,  which  is  considered 
in  Chapter  XL 

116.  Protection  of  Main  Pipe  from  Loss  of  Heat. — The 
loss  of  heat  which  takes  place  from  an  uncovered  main  steam  or 
hot-water  pipe  is,  because  of  its  isolated  position,  considerably 
greater  than  that  which  takes  place  from  an  equal  amount  of 
radiating  surface.     Unless  this  heat  is  actually  required  it  will 
cause    an    expenditure   of    fuel   the   cost    of   which    is   likely 
to   be   in  a   few  seasons   many  times  that   of   a  good   cover- 
ing. 


198  HEATING   AND    VENTILATING   BUILDINGS. 

The  heat  lost  per  square  foot  of  surface  from  a  small  un- 
covered pipe  is  from  375  to  400  heat-units  per  square  foot  per 
hour  in  steam-heating,  or  an  amount  equal  to  that  required 
for  the  evaporation  of  0.4  pound  of  steam.  Computing  this 
loss  for  100  square  feet  for  a  day  of  20  hours  and  for  a  season 
of  150  days,  it  will  be  found  equivalent  to  the  coal  required  to 
evaporate  120,000  pounds  of  steam;  this  would  not  be  less 
than  12,000  pounds  of  coal,  which  at  $5.00  per  ton  would  cost" 
§30.00.  The  cost  per  square  foot  per  annum  will  be  found  on 
the  above  basis  to  be  30  cents,  of  which  75  to  80  per  cent* 
would  have  been  saved  by  using  the  best  covering.  The 
loss  from  hot-water  pipes  would  be  about  two  thirds  of  the 
above. 

The  best  insulating  substance  known  is  air  confined  in  minute  j 
particles  or  cells,  so  that  heat  cannot  be  removed  by  convec- 
tion.    No  covering  can  equal  or  surpass  that  of  perfectly  still 
and  stagnant  air ;  and  the  value  of  most  insulating  substances 
depends  upon  the  power  of  holding  minute  quantities  in  suchl 
a  manner  that  circulation  cannot  take  place.     The  best  known 
insulating  substance  is  a  covering  of  hair  felt,  wool,  or  eider-  1 
down,  each  of  which,  however,  is  open  to  the  objection  that,  if 
kept  a  long  time  in  a  confined  atmosphere  and  at  a  temperature 
of   150  degrees  or  above,  it  becomes  brittle  and  partly  loses  1 
its  insulating  power. 

A  covering  made  by  wrapping  three  or  more  layers  of 
asbestos  paper,  each  about  -^  inch  thick,  on  the  pipe,  cover- 
ing with  a  layer  of  hair  felt  f  inch  in  thickness,  and  wrap- 
ping the  whole  with  canvas  or  paper,  is  much  used.  This 
covering  has  an  effective  life  of  about  5  years  on'  high-pressure 
steam-pipes  and  10  to  15  years  on  low-temperature  pipes. 
There  are  a  large  number  of  coverings  regularly  manufactured 
for  use,  in  such  a  form  that  they  can  be  easily  applied  or 
removed  if  desired.  There  is  a  very  great  difference  in  the 
value  of  these  coverings ;  some  of  them  are  very  heavy  and  j 
contain  a  large  amount  of  mineral  matter  with  little  confined 
air,  and  are  very  poor  insulators.  Some  are  composed  entirely 
of  incombustible  matter  and  are  nearly  as  good  insulators  as 
hair  felt.  In  general  the  value  of  a  covering  is  inversely  pro- 
portional to  its  weight — the  lighter  the  covering  the  better  its 


VARIOUS  SYSTEMS  OF  PIPING.  1 99 

insulating  properties ;  other  things  being  equal,  the  incombus- 
tible mineral  substances  are  to  be  preferred    to   combustible 
material.     The  following  table  gives 'the  results  of  some  actual 
tests  of  different  coverings,  which  were  conducted  with  great 
care  and  on  a  sufficiently  large  scale  to  eliminate  slight  errors  of 
observation.     In  general  the  thickness  of  the  coverings  tested 
was  i  J^i.     Some  tests  were  made  with  coverings  of  different 
[thicknesses,  from  which  it  would   appear  that   the  gain  in  in 
sulating  power  obtained   by   increasing  the   thickness  is  very 
slight  compared  with  the  increase  in  cost.     If  the  material  is  a 
igood  conductor  its  heat-insulating   power  is  lessened    rather 
[than  diminished  by  increasing  the  thickness  beyond  a  certain 
point. 

^PERCENTAGE  OF  HEAT  TRANSMITTED  BY  VARIOUS  PIPE- 
COVERINGS,  FROM  TESTS  MADE  AT  SIBLEY  COLLEGE, 
CORNELL  UNIVERSITY,  AND  AT  MICHIGAN  UNIVERSITY.* 

Relative  Amount 
Kind  of  Covering.  of  Heat 

Transmitted. 

Naked  pipe 100. 

[Two  layers  asbestos  paper,  I  in.  hair  felt,  and  canvas  cover 15.2 

[Two  layers  asbestos  paper,  i   in.  hair  felt,  canvas  cover,  wrapped  with 

manilla  paper 15 . 

Two  layers  asbestos  paper,  i  in.  hair  felt 17. 

Hair  felt  sectional  covering,  asbestos  lined 18.6 

One  thickness  asbestos  board 59-4 

Four  thicknesses  asbestos  paper 50 . 3 

;  Two  layers  asbestos  paper , 77 . 7 

Wool  felt,  asbestos  lined 23.1 

;  Wool  felt  with  air  spaces,  asbestos  lined 19.7 

Wool  felt,  plaster  paris  lined 25.9 

Asbestos  molded,  mixed  with  plaster  paris 31.8 

Asbestos  felted,  pure  long  fibre 20.  i 

Asbestos  and  sponge , 18 . 8 

Asbestos  and  wool  felt 20.8 

Magnesia,  molded,  applied  in  plastic  condition 22.4 

Magnesia,  sectional   iS.8 

Mineral  wool,  sectional " .     ICj .  3 

Rock  wool,  fibrous \ 20 . 3 

Rock  wool,  felted 20! 9 

Fossil  meal,  molded,  £  inch  thick 29 . 7 

Pipe  painted  with  black  asphaltum 105 . 5 

Pipe  painted  with  light  drab  lead  paint 108 . 7 

Glossy  white  paint 95. o 

*  These  tests  agree  remarkably  well  with  a  series  made  by  Prof  M.  E. 
Cooley  of  Michigan  University,  and  also  with  some  made  by  G.  M.  Brill, 
Syracuse,  N.  Y.,  and  reported  in  Transactions  of  the  American  Society  of 
Mechanical  Engineers,  vol.  xvi. 


200 


HEATING   AND    VENTILATING   BUILDINGS. 


The  following  table  translated  from  Peclet's  Traite  de  la 
Chaleur  gives  in  a  general  way  the  amount  of  heat  transmitted 
through  coverings  of  various  kinds  and  of  different  thicknesses  ; 
the  loss  from  a  naked  pipe  is  taken  as  100. 

LOSS  OF   HEAT    THROUGH    VARIOUS    PIPE-COVERINGS. 


ti, 

| 

Thickness,  in  inches. 

"3 
TJ 
C 
O 

u 

0.4 

0.8 

I.O 

1.6 

2.0 

4.0 

6.0 

Kind  of  Covering. 

01 

1 

Relative  Loss  of  Heat. 

0.04 

29 

20 

1  8 

13 

II 

7 

6 

Eider  down,  loose  wool,  hair  felt,  etc. 

0.08 

43 

32 

29 

23 

20 

13 

ii 

Powdered  charcoal. 

0.16 

56 

48 

45 

38 

35 

25 

22 

Wood  across  fibres. 

0.32 

66 

63 

62 

58 

55 

44 

41 

Sand. 

0.64 

73 

73 

73 

72 

70 

68 

Clayey  earth. 

1.28 

77 

83 

85 

92 

96 

102 

109 

Stone,  rock. 

2.56 

78 

87 

103 

no 

130 

150 

White  marble. 

5.12 

79 

90 

95 

109 

118 

149 

1  80 

Solid  gas  carbon. 

10.00 

IOO 

IOO 

IOO 

IOO 

IOO 

IOO 

IOO 

Naked,  or  unprotected  surface,  iron* 

CHAPTER   X. 
DESIGN  OF   STEAM   AND   HOT-WATER  SYSTEMS. 

A 

117.  General  Principles. — The  general  problem  of  design 
includes  the  proportioning  of,  first,  the  amount  of  radiating 
surface  which  will  be  located  directly  in  the  rooms  to  be 
heated  in  all  systems  of  direct  heating,  and  in  the  air-passages 
or  flues  leading  to  the  rooms  in  all  cases  of  indirect  heating  ; 
second,  the  size  of  the  pipes  which  are  to  convey  the  heated 
[fluids  to  the  radiating  surfaces  ;  and  third,  the  proper  size  of 
boiler  or  heater. 

The  question  of  the  system  or  method  of  heating  which  is 
;to  be  adopted  will  usually  depend  upon  considerations  of  cost 
or  of  personal  preference  on  the  part  of  the  proprietor.  The 
various  systems  of  heating,  whether  by  steam,  hot  water,  or 
hot  air,  as  commonly  practised  in  this  country,  do  not  often 
come  in  direct  competition.  Hot-air  heating,  where  the  air  is 
moved  by  natural  draft,  is  adapted  only  to  the  smaller  sizes 
of  dwelling-houses,  and  where  heat  does  not  need  to  be  carried 
fkny  considerable  distance  horizontally.  It  is  generally  found 
that  if  the  horizontal  distance  exceeds  15  or  20  feet  the  supply 
of  heat  becomes  uncertain  in  amount.  With  steam  and  hot- 
water  heating  there  is  no  such  limitation  as  to  distance ;  the 
first  cost  is,  however,  considerably  greater  than  that  of  hot  air, 
|t>ut  heat  can  be  supplied  with  certainty  to  all  parts  of  the  sys- 
tem under  all  atmospheric  conditions.  Regarding  the  relative 
merits  of  systems  of  steam  and  hot-water  heating,  little  can 
be  said.  It  will  generally  be  found  that  the  first  expense  of 
steam-heating  is  considerably  less,  and  that  there  is  considerable 
difference  of  opinion  regarding  the  relative  economy  of  oper- 
ation of  steam  and  hot-water  heating  plants.  The  tests  which 
have  been  made  have  generally  shown  somewhat  in  favor  of 

201 


2O2  HEATING   AND    VENTILATING   BUILDINGS. 

water.*     The  difference,  however,  is  not   great,  and   may 
due  to  local  conditions,  but  is  probably  due  to  the  fact  that 
the   temperature   of  the   discharged  gases   may  be  somewhat 
lower  for  the  hot-water  heater  than  for  the  steam-boiler,  and 
also  to  the  fact  that  in  comparatively  mild  weather  the  fire  in 
the  hot-water  heater   may  be   regulated   somewhat   closer,  to 
meet  the  demand  for  heat.     The  hot-water  system  in  general 
requires  rather  better  workmanship  in   the  erection   of  pipe' 
lines  than  steam-heating,  and  more  care  must  be  taken  in  pro-| 
portioning  the  various  pipes  and  fittings.     The  heat  from  hot-| 
water  radiators  is  somewhat  less  in  intensity  and  more  pleasant 
than  that  from  steam-radiators,  and  the  temperature  can  be 
regulated  by  simply  throttling  the  supply-pipe  of  the  radiators,i 
which  is  not  the  case  with  steam. 

Whether  direct  or  indirect  heating  shall  be  used  will  de- 
pend also  on  circumstances.  It  will  be  found  that  in  general 
the  surface  required  for  indirect  heating  is  one  third  to  one] 
half  greater  than  that  for  direct,  and  it  will  give  off  50  per  cent; 
more  heat  per  square  foot,  so  that  the  operating  expense  isJ 
practically  twice  that  of  direct  heating.  Indirect  heating  asJ 
sures  excellent  ventilation,  and  it  is  advisable  to  use  it  for 
certain  rooms  of  residences  because  of  that  fact. 

118.  Amount  of  Heat  and  Radiating  Surface  required 
for  Warming. — The  amount  of  heat  required  for  buildings 
cf  various  constructions  has  been  considered  quite  fully  in 
Chapter  III.  From  which  it  may  be  seen  (page  59)  that  in; 
ordinary  building  construction  the  amount  required  in  heatl 
units,  for  each  degree  difference  between  inside  and  outside 
temperature,  is  approximately  equal  to  the  area  of  the  glass 
surface  plus  one  fourth  the  area  of  the  exposed  wall  surfacel 
plus  one  fifty-fifth  of  the  number  of  cubic  feet  of  air  required! 
for  ventilation. 

The   air  required   for  ventilation  will  vary  with  the   con- 
ditions ;  but  in  direct  heating  it  seems  necessary  to  allow  foil 
three  changes  per  hour  in  halls,  two  in  rooms  on  first  floor, 
and  one  in  rooms  on  upper  floors.     (See  page  59.) 

*  See  Transactions  American  Society  Mechanical  Engineers,  vol.  x,  paper 
by  *he  author.     See  also  Report  Massachusetts  Experimental  Station  No.  8,4 
1 870. 


DESIG'N  OF  STEAM  AND   HOT-WATER   SYSTEMS.     2O3 

The  amount  of  heat  given  off  ^by  one  square  foot  of  radiat- 
ing surface,  as  determined  by  a  great  number  of  experiments, 
is  given  in  Chapter  IV,  from  which  it  is  seen  (pages  66  and  80) 
that  for  the  ordinary  radiating  surface,  with  a  temperature  of 
150  degrees  above  the  surrounding  air,  1.8  heat-units  will  be 
;given  off  per  square  foot  of  surface  per  degree  difference  of 
temperature  per  hour,  and  when  the  temperature  is  no  above 
the  surrounding  air  about  1.7  heat-units  are  emitted. 

The  total  heat  emitted  from  radiating  surfaces  of  different 
characters,  corresponding  to  the  average  results  of  experiments 
lis  shown  on  the  diagram,  Fig.  187,  in  which  the  horizontal 
distances  correspond  to  the  mean  difference  of  temperature 
between  the  air  in  the  room  and  the  radiator,  while  vertical 
distances,  the  value  of  which  is  read  on  the  scale  at  the  left, 
correspond  to  the  total  heat-units  transmitted  per  square  foot 
per  hour. 

To  use  the  diagram  assume  the  difference  of  temperature 
between  the  air  of  the  room  and  the  radiator,  then  look  on 
vertical  line  until  intersection  with  the  line  representing  the 
desired  condition  is  found,  thence  read  results  on  the  left. 
Thus,  for  instance,  if  the  difference  of  temperature  is  150  de- 
grees the  intersection  of  the  line  from  this  point  with  that 
representing  direct  ordinary  radiation  corresponds  to  275  heat- 
units,  and  with  that  representing  i-inch  horizontal  pipe,  375 
heat-units,  as  read  on  the  scale  at  the  left.  The  dotted  lines  in 
the  diagram  give  the  heat  transmitted  from  various  indirect 
surfaces  for  different  velocities  of  the  moving  air.  The  results 
are  to  be  found  as  for  direct  radiation,  but  the  difference  of 
temperature  is  that  estimated  from  the  mean  of  the  surround- 
ing air  and  the  radiator. 

Having  the  total  heat  required  for  warming  and  that  which 
is  given  off  from  one  square  foot  of  radiating  surface,  it  is  quite 
evident  that  the  surface  required  may  be  computed  by  the 
process  of  dividing  the  former  by  the  latter. 

Expressing  results  algebraically  we  can  produce  a  formula 
from  which  the  radiating  surface  may  be  calculated  quickly 
and  easily  as  follows : 

Let  R  equal  the  total  radiating  surface  required,  /  the  required  tem- 
perature of  the  room,  t'  the  temperature  of  the  outside  air,  T  the  tern 


204 


HEATING   AND    VENTILATING   BUILDINGS. 


units  par  square  foot  per  hour 

1  1  1  S  1  1  s  1  1 

Diagram  show 

n,T 

ital  h 

aattr 

ansmitted 

per 

squar 

e  foot  per 

hour 

71 

1 

\  ° 

rect  Iheati 
direo't  hea 

I?      \     . 
;ing  yariou 

5  velocities 

X 

In  it 

fron 

idirec 

i  mea 

t  hea 
n  ten 

ting, 
tpera 

diffe 

;ure 

'ence 
)f  air 

ofte 
surrc 

mper 
undii 

ature  to  b 
g  heater. 

i  rect 

oned 

/ 

/  / 

/ 

/ 

2 

/ 

/ 

, 

"V' 

/ 

/ 

/ 

'V 

/ 

7 

x 

/ 

^ 

// 

/ 

/ 

/ 

X1 

.    -j 

g 

7 

,' 

/ 

/ 

Xj^' 

*   /               y 

/  ,»x' 

xx 

s 

/ 

/ 

AC, 

y  % 

x'     . 

x^ 

^ 

&; 

V< 

;/ 

/ 

/ 

/x 

* 

j§ 

X^ 

'  / 

•y 

•>y 

/ 

,  / 

^ 

x! 

x'  v 

x  / 

x'' 

i 

y 

*\ 

/ 

% 

/ 

. 

'V 

'// 

x  ;y 

/ 

$/ 

* 

y 

.- 

''•<? 

*/ 

// 

/  x 

/      ^ 

^ 

' 

./ 

t 

/ 

3 

-'.? 

SfX 

/;/ 

'/. 

'V 

S 

-' 

/ 

* 

/ 

Xcx 

r. 

/ 

/  , 

s     / 

/ 

' 

7 

7 

1 

s 

s       c 

<& 

r 

& 

\;, 

^ 

X 

~o 

x 

f/  / 

/  < 

''  ,, 

'' 

/' 

x" 

s 

; 

x 

/ 

'  /  / 

/  , 

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X 

x 

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^ 

p 

x- 

^ 
r^ 

;*°" 

30C 
200 
100 

y 

'// 

V 

''    \ 

/ 

'' 

X 

x 

'  / 

x 

x' 

;^ 

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*/, 

''  / 

/, 

/ 

y 

X 

,' 

x' 

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x 

^ 

^ 

t 

''  / 

/  ,< 

'' 

s' 

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7 

X 

x' 

^ 

^ 

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/  , 

'' 

/ 

s' 

s' 

/ 

x 

^ 

X 

^ 

<'' 

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s' 

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x^ 

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x-^x 

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^ 

0 

/ 

.'2 

^ 

^ 

^x"x 

'"^^^ 

25                  50                   ;*                  100                 125                 150                 175                 200                 vzi, 
Mean   Difference  of  Temperature 

FIG.   187.—  DIAGRAM  OF  HEAT  FROM  RADIATING  SURFACES. 

(2) 


DESIGN  OF  STEAM  AND   HOT-WATER   SYSTEMS. 

perature  of  the  radiating  surface,  C  number  of  cubic  feet  in  the  room,  G 
the  number  of  square  feet  of  glass,  Wthe  external  wall-surface,  a  the 
heat  given  off  per  square  foot  of  radiating  surface  per  degree  difference 
per  hour,  r  the  number  of  times  the  air  is  to  be  changed  per  hour. 

We  have,  first,  the  heat  required  for  one  degree  difference  of  tem- 
perature as  explained,  pages  57  and  59,  which  is  approximately 

I  H=LC+G  +  W.. ,  (I> 

!  Second,  the  radiating  surface  is  H  multiplied  by  difference  of  temperature 
between  room  and  outside  air  divided  by  that  given  off  from  one  square 

Jt.     Hence  we  have 
A>         *  ~  ^      u         t  —  t     ( r    , 
•"»  —  T-T"        7T"    •*  ==  T'r        7T     —  L.   -\-  Lr 
{.*  — *)&  (.*  — v)^\55 

The  heat  required   per  degree  difference  of  temperature  between 
jrTuom  and  outside  air,  as  expressed  in  equation  (i),  must  be  computed  for 
|every  given  case.     The  other  quantities  which  constitute  a  factor  to  be 
multiplied  in  the  above  are  readily  computed  and  expressed  in  the  table 
on  p.  206,  which  is  calculated  for  a  great  variety  of  conditions. 

From  this  table  it  is  seen  that  we  need  to  multiply  the  area 
of  the  glass,  plus  \  the  ^vall  surface,  plus  —  of  the  cubic  feet  of 

mair  supplied  per  hour,  by  factors  which  are  approximately  as 
follows:  If  we  arc  to  heat  to  70  degrees  in  zero  weather  with 
fsteam  of  10  pounds  pressure,  multiply  by  ^  ;  if  we  are  to  heat 
to  60  degrees,  multiply  by  -J- ;  if  we  are  to  heat  to  50  degrees, 
multiply  by  |.     As  the  steam  pressures  increase,  these  factors 
are  reduced.     As  a  method  of   applying  the  rule  consider  a 
?•  room  20  feet  by  12  feet  floor  surface,  and  10  feet  high,  contain- 
ing 2400  cubic  feet,  in  which  the  air  is  to  be  changed  twice 
per  hour.    Suppose  that  it  has  320  square  feet  of  exposed  wall 
I  surface  and  48  square  feet  of  glass.     The  heating  surface  re- 
Equired  will  be  found  by  taking  the  area  of  the  glass,  48,  J  the 
exposed  wall,  80,  and  -^  the  cubic  contents,  which  is  equal  to 
87  ;  the  total  heating  surface  required  would  be  (48  +  80  -f- 
187)  215,  multiplied  by  the  factor  given  in  the  table,  which  is 
about   J,    so   that   the   radiating   surface    required    equals    54 
square    feet.     In  this  case  there  is  about  one  square  foot  of 
heating  surface  to  44  cubic  feet  of  space. 


OF  THE 

UNIVERSITY 
Of  » 


206 


HEATING   AND    VENTILATING   BUILDINGS. 


FACTORS    FOR    PROPORTIONING    DIRECT    RADIATORS  FOR  DIP 
FERENT    TEMPERATURES    ROOM    AND   OUTSIDE    AIR. 


Number  of  Column.         

1 

2 

3 

4 

5 

Coefficients  for  Steam  

1.6 

x-7 

1.8 

i.  9 

2.4 

Temperature 

Temperature 

Air. 

Room. 

• 

—  IO° 

I  OO° 

.61 

•54 

•43 

.31 

.19 

O 

100 

.55 

•  49 

.40 

.28 

•17 

+  10 

100 

•50 

.44 

.36 

•25 

.16 

—    IO 

80 

.42 

•38 

•31 

.23 

.145 

O 

80 

.38 

•33 

.275 

.20 

•13 

+   10 

80 

•33 

•30 

.24 

.18 

.11 

—    IO 

70 

•35 

•  32 

.262 

.19 

.122 

O 

70 

•32 

.28 

-23 

•17 

.109 

+  10 

70 

.26 

.24 

.20 

.14 

.092 

—   IO 

60 

.29 

.26 

.22 

.16 

.104 

0 

60 

.25 

.22 

.19 

.14 

.089    * 

+   10 

60 

.21 

.18 

•15 

.12 

•075 

—    IO 

50 

•23 

•23 

.18 

•15 

.037 

0 

50 

.20 

.19 

•15 

.12 

.072    ^ 

+  10 

50 

.16 

.14 

.12 

.10 

.058      ' 

Usual  conditions  of  steam-heating  correspond  to  a  mean  of  columns  twof 
and  three. 

HOT  WATER. 

(.Coefficient  1.6.) 


Temperatures  water  

140° 

1  60° 

1  80° 

200° 

212° 

-   10° 

80° 

•93 

.70 

•56 

•  47 

•42 

0 

80 

.83 

.62 

•  50 

.42 

.38 

+   !0 

-  80 

•73 

•54 

•  435 

•36 

•33 

—    IO 

70 

•71 

•55 

•45 

•38 

•35 

O 

70 

.62 

•47 

.40 

•333 

•32 

+   10 

70 

•  53 

.41 

•34 

.28 

.26 

—    IO 

60 

•54 

•  44 

.41 

•  3i 

.28 

0 

60 

•  47 

•37 

•36 

•27 

•23 

+   10 

60 

•39 

•  31 

•3i 

•27 

.21 

—    10 

50 

.41 

•33 

.25 

•25 

•255 

O 

50 

•38 

.28 

•30 

.20 

.196 

-f  10 

50 

•275 

.225 

.20 

•175 

.156 

1 

The  radiating  surface  is  in  each  case  found  by  multiplying  heat  as  require 
to  supply  loss  from  building  per   degree  difference  of  temperature  inside  am 


outside  by  factor  as  given  in  the  table.     This  factor  is 


in  formula  (2). 


DESIGN  OF  STEAM  AND    HOT-WATER   SYSTEMS. 

For  a  room  with  the  same  dimensions  but  on  the  second 
floor  the  quantities  will  be  computed  in  the  same  way,  except 
that  we  will  take  -^  of  the  cubic  contents  to  supply  that  re- 
'quired  by  ventilation,  so  that  the  total  heat  required  for  one 
Kegree  difference  of  temperature  would  be  48  -f-  80  +  44  =  172. 
One  fourth  of  this  quantity  gives  the  radiating  surface  for  low- 
Spressure  steam-heating,  which  in  this  case  would  be  43,  or  one 
bquare  foot  of  heating-surface  to  55  cubic  feet  in  the  room. 
|For  hot-water  heating  the  method  of  computation  would  be 
exactly  the  same,  but  the  factor  would  be  0.4  instead  of  J. 
•the  radiating  surface  would  then  be,  for  the  case  considered, 
|>.4  of  216,  which  is  86,  or  one  to  28  cubic  feet  for  a  room  on 
ihe  first  floor,  and  0.4  of  172  or  69  square  feet,  which  is  in 
•ratio  of  I  to  35  cubic  feet  for -the  second  floor. 

Many  designers  of  heating  apparatus  compute  the  amount 
of  radiating  surface  required  by  approximate  "  rules-of-thumb  " 
which  are  in  current  use  in  their  localities.  These  rules  differ 
In  many  cases  very  greatly  from  each  other,  and  often  have  to 
pe  modified  materially  in  order  to  give  satisfactory  results.  In 
{the  application  of  the  more  scientific  rules  which  have  been 
•given  there  will  still  always  be  an  opportunity  for  applying 
Kudgment  and  the  results  of  experience  and  practice,  since  it  is 
Iquite  impossible  that  any  table  of  coefficients,  no  matter  how 
•extensive,  could  be  given  which  would  apply  to  all  cases  of 
(building  construction  and  to  all  exposures.  Allowance  for  un- 
lusual  conditions  are  given  by  Mr.  Wolff  as  follows  (see  page 

IS7)' 

The  amount  of  radiating  surface  as  given  should  be  in- 
Icreased  respectively  as  follows  : 

1  Ten  per  cent  where  the  exposure  is  a  northerly  one  and  winds  are  to 
foe  counted  on  as  important  factors. 

Ten  per  cent  when  the  building  is  heated  during  the  daytime  only 
jand  the  location  of  the  building  is  not  an  exposed  one. 

Thirty  per  cent  when  the  building  is  heated  during  the  daytime  only, 
land  the  location  of  the  building  is  exposed. 

Fifty  per  cent  when  the  building  is  heated  during  the  winter  months 
[intermittently,  with  long  intervals  (say  days  or  weeks)  of  non-heating. 

Certain  allowances,  in  addition  to  the  above,  the  amount  of 
iAvhich  must  be  determined  by  the  judgment  or  experience  of 


208 


HEATING   AND    VENTILATING   BUILDINGS. 


CRUDE  ESTIMATE  OF  SPACE  HEATED  BY  i  SQ.  FT.  OF  DIREC 
STXAM-HEATING   SURFACE. 


A 

B 

c 

D 

E 

DWELLINGS. 
First  floor  

a  c  to  60 

•}«;  to  50 

Second  floor  

50  to  80 

50  to  75 

Average         ......    . 

60  to  So 

CQ 

Living  rooms  

eo 

CQ 

2  sides      '  '       

45 

0            "                             " 

40 

Halls  and  bath-rooms. 

40  to  5<i< 

Sleeping  rooms  

60  to  7* 

PUBLIC  BUILDINGS. 
Offices                         * 

50  to  80 

r  60  to  80 

7O 

en  to  7fti 

Banks 

35  to  60 

7O 

50  to  So 

[  60  to  80 

60  to    8C" 

Factories         . 

35  to  60 

7C  to  1OO 

80  tO  IOC 

Stores    wholesale,  .  .  . 

75  to  IOO 

IOO 

1=0 

80  to  io|; 

"       retail 

7c 

J  OK 

"       dry-goods 

80 

'  '       dm  firs  .  , 

7O 

Assembly  halls  

7C,  to  IOO 

75  to  100 

100  to  ij: 

Auditoriums 

125  to  2OO 

75  to  100 

Churches     .  .  . 

125  to  2OO 

150  to  200 

2OO 

100  to  i§t 

Large  hotels  

12*; 

the  engineer,  should  be  made  for  unusual  construction  of  th-l 
building,  either  good  or  bad. 

The  rules  which  have  been  given  for  determining  the  amoun  j 
of  radiating  surface  are  exceedingly  numerous.  Some  of  thes-j 
rules  require  the  proportioning  of  radiating  surface,  as  iij 
Tredgold's  *  and  Hood's  f  works,  by  the  amount  of  glass 
others  by  the  amount  of  glass  and  exposed  wall  surface,:]:  bu 
the  great  majority  by  the  number  of  cubic  feet  of  space  in  tlty 
room.  The  discussion  which  has  been  given  is  sufficient  t|i 
show  that  the  amount  of  heat  required  is  a  function  of  th) 
exposed  surfaces,  so  far  as  the  loss  from  the  walls  is  concerned! 
and  of  the  cubic  contents,  so  far  as  the  supply  of  air  for  ventn 


*  "  Warming  and  Ventilating  Buildings,"  Tredgold,  1836. 

f  "  Warming  Buildings,"  Hood,  1855. 

\  John  J.  Hogan  in  Metal  Worker,  Nov.  10,  1888. 


DESIGN  OF  STEAM  AND    HOT- WATER   SYSTEMS.     2OO, 

CRUDE  ESTIMATE  OF  SPACE  HEATED  BY  i  SQ.  FT.  OF   DIRECT 
HOT-WATER   HEATING   SURFACE. 


Authority  

F. 

25  to  35 
35  to  4° 
20  to  30 

A. 

25  1050  -j 

j  20  tO  50 
)  20  tO  40 

30  to  50 

B. 

C. 

20  tO  30 

30  to  40 

G. 

H. 

E. 

iO 

28 
25 

20  tO  30 

30  to  40 

30  to  40 

40  to  50 
50  to  60 
50  to  60 

75  to  loo 
75  to  100 

DWELLINGS  
First  floor  

High  Temp 
50  to  70 
Low  Temp.  } 
30  to  50     f 

25  to  4o 

11 

25 
20  to  30 
30  to  40 

30  to  50 

30  to  50 
50  to  70 
50  to  70 

Average  

Halls  and  bath-rooms 
Sleeping  rooms  .  .. 

PUBLIC  BUILDINGS  : 

Offices  
Banks  

15  to  25 

30  to  50 
30  to  50 

35  to  50 

35  to  50 
40  to  60 
40  to  60 

30  to  60 

30  to  60 
45  to  70 
45  to  70 
45  to  70 

80  to  too 
80  to  100 
80  to  100 

j  20  tO  50 

\  25  to  50 

!20  tO  50 
25  to  50 
45  to  65 
35  to  65 
J  45  to  65 
1  35  to  65 

J  45  to  65 
1  35  to  65 
j  70  to  130 
j  80  to  125 
j  70  to  130 
(  80  to  125 

50  to  70    \ 
30  to  50    j 

50  to  70    ) 
30  to  50    l 

J-    65  to  90 
>•    65  to  90 

j-     65  to    90 
i   130  to  180 
5-  130  to  180 

Factories  

Stores,  wholesale  .  .  . 
"       retail  

"        dry-goods... 
"       drugs  

Assembly  halls  

75  to  1  30 
75  to  130 

80  to  zoo 
80  to  loo 

ation,  but  both  of  these  quantities  must  be  considered  in  order 
to  give  results  which  are  even  approximately  correct. 

In  any  locality  it  would  seem  that  the  rules  which  are  in 
common  use  when  modified  as  to  the  condition  of  buildings 

n  which  they  have  been  successfully  applied  would  be  of  con- 
siderable value ;  for  that  reason  the  preceding  tables  are  given 
showing  the  relation  of  radiating  surface  to  cubic  feet  of  space 
to  be  heated  as  stated  by  various  authorities ;  it  will  be  noticed, 

lowever,  that  there  is  such  extreme  variation  in  the  amount 
of  heating  surface  required  for  the  same  conditions  that  the 
results  are  almost  valueless,  and  indicate  that  wide  variation  is 
common  in  the  practice  of  different  designers. 

119.  The  Amount  of  Surface  Required  for  Indirect 
Heating. — For  this  case  the  heat  received  by  the  rooms  is  all 
supplied  by  air  which  passes  over  the  radiating  surfaces  and  is 
•heated  by  convection.  A  large  number  of  tests  have  been 
quoted  of  these  heaters,  both  with  natural  and  mechanical  draft 


210  HEATING  AND    VENTILATING  BUILDINGS. 

(see  Article  52,  page  79).  From  these  experiments  it  is  seen 
that  the  amount  of  heat  given  off  by  one  square  foot  of  surface 
varies  with  the  velocity  of  the  air,  as  shown  by  the  table  on 
page  84  and  also  in  the  diagram  Fig.  187,  the  use  of  which  has 
been  explained.  From  the  table  on  page  84  it  will  be  noticed 
that  with  natural  circulation  the  velocity  in  feet  per  second 
will  vary  from  2.97  for  a  height  of  5  feet  to  8.4  for  a  height 
of  50  feet,  and  the  corresponding  convection  expressed  in- 
heat-units  per  degree  difference  of  temperature  per -square  foot 
per  hour,  which  in  the  preceding  table  is  termed  the  coefficient^ 
varies  from  3  to  6. 

The  entering  air  is  brought  into  the  room  usually  at  a 
temperature  20  to  40  degrees  above  that  in  the  room.  If 
this  entering  air  is  about  IOO  degrees,  I  heat-unit  will  warm  58 
cubic  feet  I  degree,  an  amount  about  5  per  cent  greater  than 
when  the  entering  air  was  70  (see  Table  VIII). 

From  these  data  we  can  readily  compute  the  number  of 
cubic  feet  of  air  which  must  be  supplied  to  bring  in  the  neces- 
sary heat,  and  the  size  of  heating-surface  required.  The 
amount  of  heat  to  be  supplied  must  be  sufficient  to  compen- 
sate for  loss  from  the  room,  which  is  approximately  equal  to] 
the  glass  surface  +^  the  exposed  walled  surface  multiplied  byj 
the  difference  between  the  temperature  of  the  room  and  the 
outside  air,  or  it  may  be  obtained  more  exactly  from  Wolff's' 
data,  page  57.  The  number  of  cubic  feet  of  air  required  will 
be  found  by  dividing  this  quantity  by  the  excess  of  temperature 
of  the  heated  air  over  that  of  the  air  in  the  room  and  multiply- 
ing this  result  by  58. 

The  extent  of  heating  surface  in  square  feet  will  be 
obtained  by  dividing  the  number  of  cubic  feet  of  air  as 
obtained  by  the  previous  calculation  by  the  number  of  cubic 
feet  heated  by  one  square  foot  of  surface.  If  air  is  heated  to 
100°  F.  each  heat-unit  will  warm  58  cubic  feet  one  degree. 

These  results  are  better  expressed  in  shape  of  formulae  from  which 
tables  suited  for  practical  application  may  be  computed.  Let  /  equal  the 
temperature  of  the  room,  t'  that  of  the  outside  air,  t"  that  of  the  mean 
temperature  of  the  air  surrounding  the  heating  surface,  7"  that  of  the 
heated  air,  T'that  of  the  radiating  surface,  //the  heat  required  per  houri 
per  degree  difference  of  temperature  to  supply  loss  from  the  room,  a  the 


DESIGN  OF  STEAM  AND   HOT-WATER   SYSTEMS.     211 

beat  given  off  from  i  sq.  ft.  radiating  surface  per  degree  difference  of 
temperature.     We  have  the  following  formula  : 

,    Loss  from  the  room  per  hour  (/  —  t')H  =(/  —  /')  (G  +  £  W)  nearly;  (i)* 
'    Heat  brought  in  by  i  cu.  ft.  of  air  1/58(7^'  —  /)  ;        ......     (2) 

Heat  given  off  from  i  sq.  ft.  of  radiating  surface  per  hour 

=  a(T-n\     •     (3) 

'.    Cubic  feet  of  air  required  per  hour  =  -  ;      .....     (4) 

— 


Cubic  feet  of  air  heated  by  i  sq.  ft.  of  radiating  surface  per  hour 

=  1*58(7"—"?)  (see  Artide  3'.  page  39);  .     (5) 


if  _  t'}(T'  _ 
Radiating  surface  =      „,  _  t.(T  _  ',,  =  (Factor  as  in  table)  H;  .     (6) 


The  table,*  page  212,  computed  from  the  above  formulae  for 
[various  conditions  gives  a  series  of  factors  which,  multiplied 
pnto  the  building  loss  H  per  degree  difference  of  temperature, 
prill  give  the  radiating  surface  required  ;  it  also  gives  the  num- 
fcer  of  cubic  feet  of  air  heated  the  required  amount  per  square 
foot  of  radiating  surface  per  hour. 

To  use  the  table,  we  need  simply  to  know,  in  addition  to 
^temperatures,  the  probable  coefficient  of  heat  transmission, 
"all  other  conditions  being  given.  For  ordinary  indirect  heat- 
Ing,  first  floor,  the  velocity  of  air  can  be  considered  as  2  to  4 
-feet  per  second,  and  the  corresponding  value  of  this  co- 
'efficient  as  2.  For  higher  floors  the  velocity  is  higher,  and  co- 
efficients may  be  taken  as  3.  (See  page  84.)  As  an  example, 
^assume  outside  temperature  zero,  inside  temperature  70°,  and 
the  air  leaving  the  indirect  at  IOO°,  the  factor  with  which  to 
multiply  the  building  loss  to  obtain  radiating  surface  is  0.69. 
:This  is  practically  3.00  times  that  for  direct  heating.  Com- 
puting the  radiating  surface  required  for  the  same  room  as 
that  considered  in  the  case  of  direct  heating  (page  206),  in 
which  there  was  48  square  feet  of  glass  and  320  square  feet  of 
exposed  wall  surface,  and  in  which  the  total  loss  of  heat  per 
degree  difference  of  temperature  was  128  heat-units,  the  indi- 
rect surface  required  would  be  this  quantity  multiplied  by  the 
factor  0.69,  which  is  88  square  feet,  or  about  one  half  more 
than  required  in  the  calculation  for  direct  heating.  For  the 

*  In  the  table  the  term  coefficient  is  used  for  the  heat  transmitted  per  degree 


212 


HEATING   AND    VENTILATING   BUILDINGS. 


TABLE  OF  FACTORS  TO  OBTAIN    INDIRECT  HEATING  SURFACE 
AND  OF   CUBIC    FEET   OF   AIR    HEATED    PER   SQUARE  FOOT 
*     OF   SURFACE    PER    HOUR. 


Temperatures. 

B.  T.  U.—  Total  Heat 
per  Sq.  Ft.  Heater. 

Factors  for  Heater 
Surface.* 

Cu.  Ft.  Air  per  Sq.  Ft. 
Heat.  Surf,  per  Hour. 

be 

c 

4f 

fc±.l 

« 

C» 

m 

•4- 

vd 

M 

w 

«n 

4 

vd 

M 

oi 

A 

•*- 

« 

£  8 

"o   3  U 

£<"S 

Q     g 

c 

i 

.1 

c 

c 

c 

c 

c 

| 

c 
u 

c 

1 

C 
V 

c 
u 

c 
<u 

c 

V 

c 

*l 

s^s 

u 

=  <->TJ  u 

£ 

£ 

1 

S£ 

JE 

1 

S£ 

JE 

£ 

£ 

£ 

i 

£ 

i 

!fi 

u 

< 

*** 

|«S- 

a 

i 

u 

U 

d 

a 

5 

a 

$ 

U 

i 

u 

8 

u 

i 

u 

8 
u 

3 

G 

O 

U 

0 

T' 

t" 

7-'  -  t" 

(i) 

(2) 

(3) 

(4) 

(6) 

(5) 

(6) 

(7) 

(8) 

(9) 

(10) 

(") 

(12) 

(13) 

(14! 

ROOM   70°  FAHR.,  OUTSIDE   AIR  o°  FAHR.,  STEAM  PRESSURE  o  LBS.,  STEAM" 
TEMPERATURE  212°  FAHR. 


90 

45 

167 

167 

334 

SOi 

668 

1000 

I.Q2 

0.96 

0.64 

0.48 

0.32 

108 

216 

324 

432 

648 

100 

50 

162 

162 

324 

486 

648 

972 

*«47 

o-73 

0.49 

0.36 

0.24 

Q4 

188 

«Q2 

376   564 

no 

55 

157 

157 

314 

47i 

628 

042 

I.24J0.62 

0.41 

O  3I'O.2I 

88 

176 

264 

3S2 

SV8 

120 

60 

IS2 

152 

3°4 

456 

608 

912 

1.100.55 

0.37 

0.28 

0.18 

73 

147 

22O 

394 

44° 

ROOM  70°  FAHR. 


OUTSIDE   AIR  o°  FAHR.,   STEAM 
TEMPERATURE  219"  FAHR. 


PRESSURE  5  LBS.,  STEAM 


go 

45 

174 

174 

348 

522 

696 

1062 

1.72 

0.86 

o.si 

0-43 

0.28 

112   224 

336 

448i  672 

loo 

50 

169 

169 

338 

507 

676 

1015 

1.38 

0.69 

0.46 

0-34 

0.23 

196 

294 

392 

788 

IIO 

55 

164 

164 

328 

492 

056 

934 

1.18 

0.56 

0.39 

0.29 

o.  19 

86 

173 

260 

346 

S20 

120 

60 

159 

159 

477 

636 

954 

r.i6 

o-53 

o-35 

0.27 

0.17 

77 

231 

3o8 

462 

ROOM  60°  FAHR.,    OUTSIDE   AIR    o°  FAHR.,  STEAM  PRESSURE  o  LBS.,  STEAM 
TEMPERATURE  212°  FAHR. 


344 
334 
326 


ROOM   70°    FAHR.,    OUTSIDE  AIR  o°  FAHR.,  HOT  WATER   AT  TEMPERATURE 

160°  FAHR. 


80 

40 

172 

172 

90 

45 

167 

167 

IOO 

50 

162 

162 

no 

55 

157 

J57 

1 

688  1032 

668:1020 

1.66 
i  .  16 

0.83  0.55  0.41 
0.58  0.29  o  29 

0.27 

o.  19 

I25 

108 

250 
216 

375 
324 

500 
332 

75 
64 

480 

652!  972 

o.93 

0.46  0.31 

0.23 

0.15 

94 

188 

282 

376 

56 

461 

628  922 

0.89 

0.42  0.28 

0.21 

O.I4 

83 

166 

249 

332 

49 

90 

IOO 

45 
50 

"5 

IIO 

115 

IIO 

230  345 
220  330 

460 
440 

690 
660 

2.8 
2.12 

1:^6 

0.93 
0.70 

0.7  0.46 
0-530.35 

74 
64 

148 

128 

222 
IQ2 

206 

2S6 

IIO 

55 

105 

105 

2101  315 

420 

630 

i.8b 

0.93 

0.62 

0.4610.32 

SS 

no 

165,  220 

1  20 

60 

IOO 

IOO 

2OO;  3OO   4OO 

600 

1.68 

0.83 

1   1 

480 

97 

MS 

194 

ROOM   70C 


FAHR  ,    OUTSIDE   AIR   o°  FAHR.,   HOT  WATER   AT   TEMPERATURE 
180°  FAHR. 


90 

45 

135 

135 

270 

405 

540 

810  2.36 

1.18 

0.7810.570.39 

87 

X74 

261 

348,  52 

IOO 

50 

130 

130 

2(X> 

390 

S20 

780  T.  78 

0.89 

0.590.540.29 

75 

ISO 

22S 

300!  4S 

IIO 

55 

125 

I2S 

2  SO 

37S 

Soo 

75°  i-55 

0.72 

0.52  p.39'o.26 

66 

132 

198 

264  3g 

120 

60 

1  20 

1  2O 

240 

36o 

480 

720JI.4 

o-7 

o.47Jo.35jo.23 

5« 

116 

174 

232)  34 

difference  of  temperature  per  square  foot  per  hour.     Coefficients   i   to  4  corre- 
spond to  ordinary  indirect  heating. 

*To  find  surface  of  heater  multiply  loss  from  room  for  one  degree  difference 
of  temperature  by  the  factor  for  the  given  condition.  Results  computed  by 
formula  (6).  . 


DESIGN  OF  STEAM  AND   HOT-WATER   SYSTEMS.     21$ 


second  and   third  stories  the  factors  are  to  be  found  in  the 
column  in  which  the  coefficient  is  3. 

The  following  table  gives  the  number  of  cubic  feet  of  air 
required  per  hour  in  indirect  heating  to  maintain  the  proper 
temperature,  as  computed  by  formulae  (4),  for  each  heat-unit 
rlost  from  walls  and  windows  of  room  for  a  temperature  of  60° 
or  70°  above  outside  air.  The  total  air  required  will  be  found 
my  multiplying  the  values,  as  given  in  the  table,  by  the  total 
heat  lost  per  degree  difference  of  temperature  from  the  room. 
iDiis  loss  is  designated  by  H  in  formulae  (4),  and  is  approxi- 
mately equal  to  the  glass  plus  £  the  exposed  wall  surface  ex- 
pressed in  square  feet.  (See  page  59.) 


CUBIC    FEET   OF   AIR  PER    HEAT-UNIT   FROM    WALLS. 


Temperature  of  Room, 

Temperature 
of  Entering  Air 
above  that  of 

Degrees  Fahr. 

Room. 

60° 

70° 

IO 

34S 

406 

2O 

174 

203 

30 

116 

135 

40 

3? 

103 

50 

70 

Si 

60 

53 

63 

70 

49 

58 

80 

44 

5i 

90 

36 

45 

IOO 

35 

4i 

Thus  to  find  the  number  of  cubic  feet  of  air  required  to 
\  warm  a  room  to  70°  in  zero  weather,  in  which  the  glass  plus 
Kone  fourth  the  exposed  wall  surface  equals  128,  and  air  is  in- 
i  troduced  30°  above  that  in  the  room,  multiply  135,  as  given  in 
;  the  table,  by  128. 

It  is  usual  to  allow  50  per  cent  more  surface  for  indirect 
than  for  direct  heating,  although  some  engineers  allow  only 
i  25  per  cent  more. 

In  concluding  this  subject  it  may  be  remarked  that  the 
amount  of  heat  which  is  given  off  from  indirect  heating 
surfaces  would  seem  from  the  experiments  to  depend  largely 


214 


HEATING   AND    VENTILATING   BUILDINGS. 


on  construction.  With  the  surface  erected  closely  together 
the  amount  is  small.  By  better  arrangement  of  the  surfaces, 
so  that  all  parts  are  made  hot,  and  an  ample  opportunity  is 
provided  for  circulation  of  the  air,  the  coefficient  of  heat  trans- 
mission may  be  much  increased.  If  extended-surface  radia- 
tors are  used  and  the  entire  surface  figured  as  effective,  the 
coefficient  should  be  taken  about  10  per  cent  less  than  assumed 
by  the  writer  in  the  computation.  For  forced  draft  the  coef- 
cient  may  be  safely  taken  as  4  and  6,  or  about  100  per  cent 
greater  than  for  natural  circulation. 

The  following  tables  are  collected  from  various  authorities, 
and  are  of  interest  as  showing  character  of  "  rule  of  thumb  " 
practice  in  providing  indirect  heating  surface  for  rooms  of 
various  kinds.  It  will  be  noted  that  the  amount  specified 
for  the  same  work  differs  more  than  50  per  cent,  which  shows 
the  crudeness  of  estimates  of  this  character. 


CRUDE   ESTIMATE  OF    SPACE    HEATED   BY    i    SQ.    FT.    OF    INDI- 
RECT  STEAM-HEATING   SURFACE. 


Authority     

K. 

A. 

B. 

c 

D 

DWELLINGS  : 
First  floor  

20  to  "^ 

2C  to  1=; 

40  to  50 

4O  to  co 

Average              .  .  . 

40 

4.0  to    c,o 

1Q 

Living-rooms     .  .   . 

One  side  exposed.  .  .  . 
Two  sides  exposed... 
Three  sides  exposed  . 
Halls  and  bath-rooms 

50  to  70 

50  to    70 

Sleeping-rooms  

PUBLIC  BUILDINGS  : 
Offices       

60 

j  20  to  35  ) 

40  to    50 

60 

Banks  

60 

\  40  to  50  j" 
See  DWELLINGS 

40  to    50 

60 

School-rooms  

See  DWELLINGS 

4.O  tO     5O 

Factories            .  .  . 

50  to  70 

50  to    70 

Stores,  wholesale.  .  .  . 

TOO 

70 

70 

IOO 

"       retail    

80 

CQ 

CQ  to     7O 

80 

"       drv-goods.  .  .  . 

7° 

70 

"       drugs  

60 

60 

80  to  i^c, 

ioo  to  140 

Auditoriums  

80  to  135 

ioo  to  140 

Churches  

JCQ 

80  to  i^t; 

ioo  to  140 

I  CO 

IOO 

IOO 

DESIGN  OF  STEAM  AND   HOT-WATER   SYSTEMS.     21$ 


CRUDE   ESTIMATE   OF   SPACE    HEATED    BY  i    SQ.  FT.    OF   INDI 
RECT    HOT-WATER   HEATING   SURFACE. 


Authority             

F. 

A. 

TJ 

c 

DWELLINGS: 
First  floor               

jc  to  2$ 

j  15  to    30 

30  to    60  I 

14  to  20 

20  to  30 

1  15  to    40 

2O  to     40  f 

20  to  30 

Third        " 

20  to  30 

Living-rooms    ... 

IS  tO  25 

One  side  exposed  
Two  sides  exposed  

Three  sides  exposed..  .. 
Hall  and  bath  rooms.  .  . 
Sleeping-rooms 

10  to  20 

PUBLIC  BUILDINGS: 
Offices          

25  to  40 

j  15  to    30 

30  to    60 

Banks 

(  15  to    40 

20  to    40 

School-rooms         .... 

25  to  40 

3  15  to   30 

30  to    60 

Factories  

25  to  40 

1  15  to    40 
j  30  to    45 

20  to    40 
35  to    75 

Stores    wholesale.    .  . 

2^  tO  4O 

t  25  to    50 
3  30  to    45 

25  to    50 
35  to    75 

"       retail  

25  to  40 

(  25  to    50 

25  to    50 

"       dry-goods  

"       diugs    

Assembly  halls  
Auditoriums 

50  to  80 
5O  to  80 

j  30  to    45 
/  25  to     50 
j  50  to  loo 

35  to    75 
25  to    50 
70  to  150 

Churches  

50  to  80 

(  50  to  100 
j  50  to  100 

50  to  ioo 
70  to  150 

Large  hotels 

I  50  to  ioo 

50  to  ioo 

120.  Summary  of  Approximate  Rules  for  Estimating: 
Radiating  Surface. — As  the  temperature  required  for  build- 
ings of  various  classes  varies  but  little,  and  as  the  heating  sur- 
face is  usually  estimated  to  be  sufficient  to  heat  buildings 
during  zero  weather  to  a  temperature  of  70  degrees,  some  very 
simple  rules  can  be  given  which  are  founded  on  a  rational  basis, 
and  which  with  certain  modifications,  as  explained  (page  57), 
for  those  which  are  especially  exposed,  will  be  found  to  give 
good  results  in  practice  which  agree  closely  with  those  used 
by  the  best  heating  engineers.  They  are  as  follows  : 

First.  The  amount  of  heat  required  to  supply  that  lost 
from  the  room  per  degree  difference  of  temperature  is  approxi- 
mately equal  to  the  area  of  the  glass  in  square  feet  plus  1/4  the 
exposed  ti'all  surface.  (See  page  59.) 


216  HEATING   AND    VENTILATING   BUILDINGS. 

Second.  The  heat  necessary  to  supply  loss  from  ventilation 
for  dwelling-houses,  first  floor,  is  2/55  of  the  cubic  contents  per 
hour  for  living-rooms  ; 

3/5  5  °f  the  cubic  contents  for  halls  ; 

1/55  of  the  cubic  contents  for  upper  stories. 

For  churches,  auditoriums,  the  loss  to  supply  ventilation 
should  be  t.iken  as  3/55  to  6/55  of  the  cubic  contents;  for  offices, 
banks,  etc.,  1/55  to  2/55  of  the  cubic  contents,  depending 
upon  circumstances. 

Third.  To  find  the  radiating  surface  for  direct  steam-heat- 
ing, multiply  the  sum  of  the  numbers  as  given  by  rules  First 
and  Second  by  1/4. 

Fourth.  To  obtain  the  radiating  surface  for  direct  hot- 
water  heating,  multiply  the  sum  of  the  numbers  as  given  by 
rules  First  and  Second  by  0.4.  These  rules  may  both  be 
summed  up  in  the  following  concise  form  : 

RULE. — For  heating  to  70  degrees  in  zero  weather,  direct 
heating  :  Radiating-  surface  is  equal  to  the  sum  of  the  glass  sur- 
face plus  1/4  the  exposed  wall  surface  plus  1/55  to  3/55  the 
cubic  contents,  for  rooms  as  explained,  multiplied  by  1/4  for  low- 
pressure  steam-heating  or  by  0.4  for  hot-water  heating. 

NOTE. — When  air  is  introduced  at  100  degrees   Fahr.,  58  should  be  used 
instead  of  55.     This  difference  is,  however,  usually  negligible. 

For  indirect  heating  the  following  rules  will  give  quite 
satisfactory  results  when  the  temperature  of  the  room  is  to  be 
maintained  at  70°  with  outside  air  at  zero  and  the  heated 
air  brought  in  at  a  temperature  30°  above  that  in  the  room. 
In  this  calculation  the  surface  of  the  steam  radiator  is  sup- 
posed to  be  212°,  that  of  the  hot-water  radiator  170°  Fahr. 
The  coefficients  are  taken  from  the  preceding  table. 

RULE. — The  radiating  surface  for  indirect  heating  is  equal 
to  the  glass  surface  plus  one  fourth  the  exposed  wall  surface 
in  square  feet  multiplied  by  the  following  factors: 

Steam-heating.  Hot- water  Heating. 

1st  story 0.7  1.05 

2d      "      0.6  0.9 

3d      "      0.5  0.8 

The  total  amount  of  air  supplied  will  be  given  by  the  fol- 
lowing 


DESIGN  OF  STEAM  AND   HOT-WATER   SYSTEMS.     2 1/ 

RULE. — The  air  in  cubic  feet  per  hour  is  found  by  multi- 
plying the  radiating  surface,  computed  as  in  above  rule,  by  the 
following  factors : 

Steam -heating.  Hot- water  Heating. 

ist  story 200  125 

2d       *'      250  160 

3d      "     300  200 

If  this  is  insufficient  for  ventilating  purposes  more  air  must 

introduced,  which  must  be  heated  to  70°  F.,  and  this  will 
require  approximately  an  additional  foot  of  surface  for  each 
additional  250  cubic  feet  of  air  heated  by  steam,  or  for  each 
additional  150  cubic  feet  heated  by  hot  water. 

These  rules  will  be  found  quite  simple  in  application,  and 
they  may  be  easily  committed  to  memory.  For  rooms  which 
are  poorly  constructed  or  especially  exposed  these  results 
should  be  increased  the  same  proportional  amount  as  for  direct 
radiating  surfaces.  For  temperatures  lower  or  higher  than  70° 
the  table  of  factors  p.  212  may  be  used  with  facility. 

121.  Flow  of  Water  and  Steam. — It  seems  necessary  to 
say  a  few  words  respecting  the  general  laws  which  apply  be- 
fore considering  the  practical  application.  The  velocity  with 
which  water  flows  in  a  pipe  is  computed  from  the  same  general 
laws  as  those  applying  to  the  fall  of  bodies.  The  velocity  is 
1  produced,  however,  not  by  actually  falling  through  a  given 
distance,  but  by  a  difference  of  pressure,  which  must  be  ex- 
pressed, not  in  pounds  per  square  inch,  but  in  feet  of  head. 
This  head  is  in  every  case  to  be  found  by  multiplying  the  dif- 
ference of  pressure  by  the  height  required  for  the  given  fluid  to 
make  one  pound  of  pressure.  If  we  denote  by  //  the  difference 
of  head  as  described,  by^  the  force  of  gravity  ==  32.16,  by  v 
the  velocity  in  feet  per  second,  we  would  have  in  case  of  no 
friction 


v  —  \2gh. 

The  quantity  discharged  per  second  would  be  found  in 
every  case  by  multiplying  the  velocity  by  the  area  of  the  ori- 
fice in  square  feet. 

In  the  flow  of  water  in  pipes  there  is  considerable  friction, 


218  HEATING   AND    VENTILATING   BUILDINGS. 

which  acts  to  reduce  the  velocity  and  the  amount  discharged  ; 
this  increases  with  the  length  and  decreases  with  the  diameter 
of  the  pipe.  For  the  actual  flow  we  depend  upon  experi- 
mental results.  An  approximate  formula,  attributed  by 
Robert  Briggs*  to  Prof.  Unwin,  which  is  sufficiently  accurate 
for  computing  the  flow  of  water  in  pipes  is  as  follows  : 

Let  v  =  the  velocity  in  feet  per  second,  Fthe  velocity  of 
feet  per  minute,  q  —  the  quantity  discharged  in  cubic  feet  per 
second,  Q  =  that  discharged  per  minute,  /  =  the  length  of 
pipe  in  feet,  h  —  the  head  in  feet,  D  —  the  diameter  in  feet, 
d  =  the  diameter  in  inches. 


=  0.0448 


; 


.  =  4.7233 

The  friction  caused  by  bends  and  by  passing  throng] 
valves  and  into  entrance  of  pipes  is  of  considerable  amount 
and  often  requires  consideration.  It  can  be  considered  a 
producing  the  same  resistance  to  flow  as  though  the  pipe  hac 
been  increased  in  length  certain  distances  as  follows  :  go-degree 
elbow  is  equivalent  to  increase  in  length  of  the  pipe  40  diam 
eters,  globe  valve  60  diameters,  entrance  of  a  pipe  in  tee  o 
elbow  60  diameters,  entrance  in  straight  coupling  20  diameters 

The  flow  of  steam  in  pipes  presents  some  problems  slightly 
different  from  that  of  flow  of  air  (Articles  31  and  32),  but  ii 
many  respects  the  two  cases  are  similar.     There  is  a  tendency 
for  the  steam   to  condense,  which  changes  the  volume  flow 
ing  and  affects  the  results  greatly.     The  effect  of  condensa 
tion    and    friction    is   to   reduce  the  pressure   in  the  pipe  an 
amount  proportional  to  the  velocity  and  also  to  the  distance 
and  these   losses  are  greater  as  the  pipe  is  smaller.     There 

*  Steam-heating  for  Buildings,  p.  75,  by  Briggs. 


DESIGN  OF  STEAM  AND   HOT-WATER   SYSTEMS.     2IQ 

seems  to  be  very  little  exact  data  regarding  the  steady  flow  of 
steam  in  pipes,  and  it  has  been  customary  for  writers  to  assume 
that  the  same  laws  which  apply  to  the  flow  of  water  hold  true 
in  this  case,  and  that  the  same  methods  can  be  used  in  com- 
puting quantities.  These  results  are  certainly  safe,  although 
.no  doubt  giving  sizes  somewhat  larger  than  strictly  necessary 
for  the  purposes  required. 

In  estimating  the  size  of  steam-pipe  for  power  purposes  it 

is  customary  to  figure  the  area  of  cross-section,  such  as  giving 

m  velocity  of   flow  not  exceeding  100  feet  per  second.     This 

^velocity  is  generally  accompanied  by  a  reduction  of  pressure 

,in  a  straight  pipe  of  about  one  pound  in  100  feet.     For  steam- 

peating  purposes  the  general  practice  is  to  use  a  much  larger 

•pipe  and  lower  velocity,  so  that  the  total  reduction  in  pressure 

on  the  whole  system  is  much  less ;  the  effect  of  a  drop  in  pres- 

pure  of  one  pound  will  cause  the  water  to  stand  in  the  return 

fcipe  in  a  gravity  system  2.4  ft.  above  the  water-level  in  the 

boiler. 

The   velocity  of  water  and   steam   in   a  gravity  system  of 
Bleating  is  due  to  a  different  cause   from  that  in  the  case  just 
•considered,  for  the  reason  that  the  pressure  upon  the  heater 
iacts  uniformly  in  all  directions,  and  exerts  the  same  force  to  pre- 
^vent  the  flow  into  the  boiler  from  the  return,  as  to  produce  the 
flow  into  the  main.     For  such  cases  the  sole  cause  of  circula- 
rtion  must  be  the  difference  in  weight  of  the  heated  bodies,  hot 
water,  or  steam  in  the  ascending  column  and  the  cooler  and 
'heavier  body  in  the  descending  column.     The  velocity  induced 
by  a  given  force  will   be  reduced    in  proportion  as  the   mass 
Amoved  is  greater.     In  the  case  of  steam-heating  the  difference 
between  the  weight  in  the  ascending  and   descending  column 
is  so  great  that   the  velocity  will   not  be  essentially  different 
^frorn  that  of  free  fall,  provided  correction  is  made  for  loss  of 
head  due  to  friction,  etc.,  as  Explained,  but  in  case  of  hot  water 
the  theoretical  velocity  produced  will  be  found  very  small. 

The  case  is  very  similar  to  the  well-known  problem  in 
mechanics  in  which  two  bodies  A  and  B  of  unequal  weights 
are  connected  by  a  cord  passing  over  the  frictionless  pulley  C 
(Fig.  190). 


220 


HEATING   AND    VENTILATING   BUILDINGS. 


The  heavier  body  £  in  its  descent  draws  up  the  lighter  body  A.  Ir 
this  case  the  moving  force  is  to  the  force  of  gravity  as  the 
difference  in  the  weights  is  to  the  sum  of  the  weights,  ant 
the  velocity  is  the  square  root  of  twice  the  force  into  the 
height. 

In  other  words,  if/  equals  the  moving  force,  we  haw- 
by  proportion 

f\g\\  B  —  A  :  B  +  A, 
from  which 

_     B.~  A 

f  ~g  B +  A' 

which,  substituted  in  place  of /in  formula  v  =  t/2///,  gives 
the  following  as  the  velocity : 


h  being  the  height  fallen  through. 

In  applying  this  to  the  case  of  hot-water  heating  we  have,  instead  of 
the  descent  and  ascent  of  two  solids  of  different  weights,  the  descent 
and  ascent  of  columns  of  water  connected  as 
shown  in  Fig.  191,  the  heated  water  rising  in 
the  branch  AJ^  and  the  cooler  water  descending 
in  the  branch  BC.  The  force  which  produces 
the  motion  is  the  difference  in  weight  of  water 
in  the  two  columns;  the  quantity  moved  is  the 
sum  of  the  weight  of  water  in  both  columns. 
This  is  equal  to  the  difference  in  weight  of 
i  cubic  foot  of  the  heated  and  cooled  water 
divided  by  the  sum,  multiplied  by  the  total 
height  of  water  in  the  system,  so  that  if  W\ 
represents  the  weight  of  i  cubic  foot  in  the 
column  BC,  and  W  represents  the  weight  of  i 
cubic  foot  in  the  column  AF,  and  h  represents 
the  total  height  of  the  system,  then  the  velocity 
of  circulation  will  be,  in  feet  per  second, 


(W,  +  W) 


FIG.  191. — CIRCULATION 
IN  HOT- WATER  PIPES! 


In  this  formula  no  allowance  whatever  is  made  for  frictioil 
consequently  the  results  obtained  by  its  use  will  be  much  in 
excess  of  that  actually  found  in  pipes.  The  amount  of  fric| 
tion  will  depend  upon  the  length  of  pipe  and  its  diameter! 
As  result  of  experiment  the  writer  found  considerable  variation 


DESIGN  OF  STEAM  AND    HOT-WATER   SYSTEMS.     221 


in  different  measurements  of  velocity,  but  in  no  case  did  he 
find  a  velocity  greater  than  that  indicated  by  the  formula. 
The  following  table  is  calculated  from  the  formula  without 
allowance  for  loss  by  friction.  The  computation  is  made  with 
the  colder  water  at  160  degrees  F.,  although  little  difference 
would  be  found  in  calculations  at  other  temperatures. 

VELOCITY   IN   FEET    PER   SECOND    IN    HOT-WATER    PIPES. 


o  c 

"*  u 

Difference  of  Temperature. 

•£•28 

•2 

fl* 

!- 

i° 

5° 

10° 

15° 

20° 

30° 

4o° 

i 

8.03 

0.107 

0.242 

0-335 

0.412 

0.478 

0-593 

0.672 

5 

17.9 

0.232 

0.541 

0.750 

0.922 

1.09 

1-33 

1.51 

10 

25-4 

0.328 

0.765 

1.  06 

1.32 

1-55 

1.88 

2.14 

20 

35-9 

0.463 

1.085 

I.Jj 

1.85 

2.19 

2.66 

3.01 

30 

43-9 

0.567 

i-33 

1.83 

2.26 

2.68 

3-26 

3-71 

40 

50-7 

0.656 

i-53 

2.12 

2.61 

3.08 

3-76 

4.26 

50 

56.7 

0.732 

1.71 

2-37 

2.82 

3-47 

4.22 

4-77 

60 

62.1 

O.8O2 

1.88 

2-59 

3.20 

3-79 

4.62 

5.22 

70 

67.1 

0.866 

2.02 

2.80 

3-45 

4.08 

4-97 

5.65 

80 

71.8 

0.925 

2.16 

3-o 

3-69 

4-37 

5.32 

6.03 

90 

76.1 

0.932 

2.27 

3.18 

3-91 

4.64 

5-64 

6.41 

100 

80.3 

1.037 

2.42 

3-35 

4.13 

4.78 

5-93 

6.72 

This  table  is  of  interest  for  the  reason  that  most  computa- 
tions of  the  velocity  of  circulation  of  hot  water  have  entirely 
neglected  the  effect  that  the  mass  or  weight  of  the  water  moved 
has  on  the  velocity,  and  hence  the  results 
as  computed  have  been  many  times  greater 
than  actually  found.  The  method  usually 
employed  in  computing  this  velocity  has 
been  to  consider  the  denser  and  lighter 
fluids  occupying  the  relative  positions  shown 
in  Fig.  192,  the  lighter  fluid  being  in  one 
branch  of  the  U  tube,  the  heavier  in  the 
other.*  If  the  cock  be  opened,  equilibrium 
will  be  established,  and  the  lighter  liquid 
will  stand  in  the  branch  higher  than  the 
heavier  a  distance  sufficient  to  balance  the 
difference  in  weight.  If  we  suppose  (i)  the  cock  closed  and 


*  See  Hood's  work  on  "  Warming  Buildings,"  page  27.     So  far  as  the  writer 
knows,  this  theory  has  not  before  been  questioned. 


222  HEATING   AND    VENTILATING   BUILDINGS. 

enough  of  the  heavier  material  added  to  the  shorter  column, 
that  the  heights  in  each  are  the  same ;  (2)  the  cock  opene< 
then  the  heavier  liquid  will  move  downward  and  drive  the 
lighter  liquid  upward  with  a  velocity  said  to  be  equal  to  that; 
which  a  body  would  acquire  in  falling  through  the  distance 
equal  to  the  difference  in  heights  when  the  columns  were  in; 
equilibrium.  This  gives  too  great  results,  because  it  neglects- 
the  effect  of  the  mass  of  the  bodies  moved.  If  friction  be  con- 
sidered, we  should  have  as  a  probable  expression  of  velocity^ 
using  the  same  notation  as  on  page  218, 


=  qo      A^-  W}hV 
V  W+  W}    I  ' 


122.  Size  of  Pipes  to  supply  Radiating  Surfaces. — Thef 
method  of  computing  the  size  of  pipes  required  for  stearrl 
heating  would  be  as  follows :  First  find  the  amount  of  stearrl 
by  dividing  the  total  number  of  heat-units  given  out  by  \\ 
square  foot  of  radiating  surface  by  the  latent  heat  in  I  pound? 
of  steam,  this  will  give  the  weight  of  steam  required  per  square! 
foot;  this  multiplied  by  the  number  of  cubic  feet  in  I  pound] 
of  steam  will  give  the  volume  which  will  be  required  for  eachj 
square  foot  of  radiating  surface.  Knowing  this  quantity  thel 
size  of  pipe  may  be  computed  from  the  considerations  already] 
given,  either  by  formulae  of  Article  121  or  by  assuming  the! 
velocity  of  flow  as  equal  that  due  to  the  head,  corrected  for 
friction  ;  25  to  50  feet  per  second  can  in  nearly  every  case  be' 
realized.  As  an  illustration  ;  compute  the  size  of  main  steam-j 
pipe  required  to  supply  1000  feet  of  radiating  surface  with: 
steam  at  a  temperature  of  212  degrees  when  the  surrounding^ 
temperature  of  the  air  is  70:  For  this  case  I  square  foot  of 
radiating  surface  can  be  assumed  ordinarily  as  giving  off| 
(1.8  times  142)  255  heat-units.  To  supply  1000  feet  of  surface! 
255,000  heat-units  per  hour  would  be  required ;  as  each  pound] 
of  steam  during  condensation  (see  steam  table)  will  give  up! 
966  heat-units,  we  will  need  for  this  purpose  264  pounds  per] 
hour;  and  as  each  pound  of  steam  at  this  temperature  makes 
26.4  cubic  feet,  we  will  require  6970  cubic  feet  of  steam  per 
hour,  or  1.94  cubic  feet  per  second. 

If  we  proportion   the  pipes  so  that  the  velocity  shall  not] 


DESIGN  OF  STEAM  AND    HOT-WATER   SYSTEMS.     22$ 


exceed  25  feet  per  second,  the  area  of  the  pipe  must  be  0.077 
square  foot,  which  equals  n.i*  square  inches.  For  this  we 
would  require  a  pipe  4  inches  in  diameter.  If  we  had  as- 
sumed the  velocity  to  be  50  feet  per  second,  the  area  would 
Save  been  5.6  square  inches  and  the  diameter  3  inches ;  if  we 
had  assumed  a  velocity  of  100  feet  per  second,  the  area  required 
fwould  have  been  2.8  square  inches  and  the  diameter  of  the 
:pipe  required  would  have  been  somewhat  less  than  2  inches. 
tThe  friction  in  a  pipe  when  steam  is  moving  at  a  velocity  of 
^100  feet  per  second  causes  a  reduction  in  pressure  of  about  ij 
^pounds  in  100  feet,  a  velocity  of  50  feet  per  second  causes 
about  J  as  much,  and  a  velocity  of  25  feet  about  T^  as  much. 
^Indirect  surfaces  of  the  same  extent  usually  require  twice  as 
?irmch  steam  and  a  pipe  with  area  twice  as  great  as  that  needed 
for  direct  radiation. 

For  the  single-pipe  system  of  heating  an  additional  amount 
pf  space  must  be  provided  in  the  steam  main  to  permit  the 
freturn  of  the  water  of  condensation.  The  actual  space  occupied 
by  the  water  is  small  compared  with  that  taken  by  the  steam, 
'but  in  order  to  afford  room  for  the  free  flow  of  the  currents 
lof  water  and  steam  in  opposite  directions,  experience  indicates 
^that  about  50  per  cent  more  area  should  be  provided  than  is  re- 
jfquired  in  the  separate  return  or  double  pipe  system  of  heating. 

By  similar  computations  we  obtain  the  following  factors, 
which  are  to  be  multiplied  by  the  radiating  surface  to  obtain 
areas  and  diameters  of  steam-heating  mains  in  inches : 

TABLE  FOR  AREA  AND  DIAMETER  OF  STEAM-MAIN. 


Velocity  of 
steam,  feet 
per  second. 

(i) 

Multiply  each  100  sq.  ft. 
radiating  surface  for 
area  steam  main  by 

(«) 

Multiply  sq.  root  radiating 
surface  for  diam.  by 

(3) 

Probable  fric- 
tional  resist- 
ance per  ioo  ft., 
inches  water. 

<  4) 

Required 
steam 
pressures. 
Lbs. 
(5) 

25 

37-5 
50 
62.5 

75 

100 

Double-pipe 
system. 
.90 

.675 
•45 
•375 
-30 
.225 

Single-pipe 
system. 

1-35 
1.  01 

0.67 
0.56 
0-45 
0-34 

Double-pipe 
system. 
.107 
.052 
.075 
.069 
.062 
.054 

Single-pipe 
system. 

-131 

•113 
.092 
.090 

•075 
.066 

2.O 

6.0 
8.0 

12.6 

18 
32.0 

*  o  to  i 
2  to  3 
3  to  4 
4  to  5 
5  to  6 
6  to  40 

In  all  cases  if  the  mains  are  not  covered,  its  surface  is  to  be  estimated  as  a 
part  of  the  radiating  surface. 

*  This  quantity  is  greater  than  the  area  of  a  3^-inch   pipe,  and  in  such  case 
the  safe  proceeding  is  to  use  the  next  greater  size. 


224  HEATING   AND    VENTILATING   BUILDINGS. 

The  table  on  page  223  gives  in  the  first  column  the  velocity 
of  steam,  in  the  second  column  the  corresponding  area  of  pipe 
in  square  inches  required  for  each  100  square  feet  of  radiating 
surface  for  the  double  and  single  pipe  systems  of  heating,  in 
the  third  column  the  diameter  of  pipe  for  each  square  foot 
of  radiating  surface  for  both  systems  of  heating,  which  latter 
is  to  be  multiplied  by  the  square  root  of  the  given  radiating 
surface,  to  obtain  the  diameter  required.  Column  4  gives  the 
approximate  back  pressure  in  inches  of  water  per  100  feet  ini 
length  of  the  main  for  steam  having  the  same  velocity  as  inj 
column  I.  Column  5  suggests  steam-pressures  which  will 
render  any  of  these  values  satisfactory  in  practice. 

As  an  example  showing  use  of  table,  suppose  that  a  main 
pipe  to  supply  650  square  feet  of  radiating  surface  is  needed  in 
a  single-pipe  system  in  which  the  back  pressure  shall  be  about 
12  inches  of  water-column  per  100  ft.  of  length.  The  assumed 
resistance  is  found  in  column  4  and  corresponds  to  a  velocity  of 
about  62.5  feet  per  second. 

Column  2  gives  the  factor  for  the  area  of  pipe  as  0.56,  which, 
multiplied  by  6.50,  gives  3.64  sq.  in.  as  the  required  area.  The 
diameter  can  be  obtained  from  this  result  or  computed  by; 
multiplying  the  square  root  of  the  radiating  surface  by  the 
number  in  column  3.  The  square  root  of  650  is  25.4.  This 
multiplied  by  0.09  gives  the  diameter  required  as  2.3  in.  For 
this  case  a  2^-inch  pipe  must  be  used.  For  the  double-pipe 
system,  the  factor  for  area  would  be  0.375  and  that  for  diameter 
would  be  0.069.  The  required  pipe  for  the  case  considered 
would  have  a  diameter  of  1.75  in.  The  size  next  largest,  viz., 
2.0  in.  should  be  used  for  the  steam-main.  For  calculating  re- 
turn see  Article  123. 

Most  of  the  rules  which  have  been  given  for  determining 
sizes  of  steam-pipe  when  the  radiating  surface  only  is  given  will 
be  found  included  in  the  tabulated  values.  Thus  Mr.  George  H. 
Babcock  gives  a  rule  for  gravity  heating-systems  with  separate 
returns  as  follows  :*  "  The  diameter  of  the  mains  leading  from 
the  boiler  to  the  radiating  surface  should  be  equal  in  inches  to 
one  tenth  the  square  root  of  radiating  surface,  mains  included, 

*  Transactions  American  Society  Mechanical  Engineers,  May,  1885. 


DESIGN  OF  STEAM  AND   HOT-WATER   SYSTEMS.     22$ 

in  square  feet."  This  rule  is  also  adopted  by  William  J.  Bald- 
win, and  given  in  his  book  on  "  Steam-heating."  *  By  consult- 
ing the  table  already  given,  column  3,  this  factor  would  corre- 
spond to  a  velocity  of  steam  slightly  exceeding  25  feet  per 
second,  and  would  be  adapted  for  low-pressure  steam-heating 
in  small  plants. 

One  authority  f  gives  the  following  rules  for  determining 
the  cross-sections  of  area  of  pipes  :  "  For  steam-mains  and 
returns  it  will  be  ample  to  allow  a  constant  of  0.375  °f  a  square 
;Jnch  for  each  100  square  feet  of  heating  surface  in  coils  and 
radiators,  0.375  °f  a  square  inch  when  exhaust  steam  is  used, 
'0.19  of  a  sq.  inch  when  live  steam  is  used,  and  0.09  of  a  square 
tfnch  for  the  return.  Steam-mains  should  never  be  less  than 
ij  inches,  nor  the  returns  less  than  three  fourths  of  an  inch,  in 
diameter."  Mr.  Alfred  R.  Wolff  uses  a  table  which  is  com- 
puted by  formulae  similar  to  those  given  on  page  218  for  ob- 
taining the  capacity  of  steam-mains  of  a  given  diameter,  the 
capacity  being  expressed  both  in  heat-units  delivered  and  in 
.radiating  surface.  This  table  is  given  on  page  2260  and  will 
be  found  convenient  and  accurate. 

The  size  of  main  steam-pipe  depends  on  the  consideration 
already  given  ;  the  smaller  the  size  the  greater  the  resistance  of 
the  steam  and  the  more  friction  and  consequent  back  pressure 
on  the  system  ;  the  larger  the  pipes  that  are  used  the  less  the 
resistance,  and,  in  general,  the  more  satisfactory  the  results, 
!but  economy,  of  course,  forbids  the  use  of  pipes  beyond  a  cer- 
>tain  size,  and  that  size  should  be  selected  by  considerations 
relating  to  pressure,  velocity  of  steam,  and  friction,  as  ex- 
plained. 

The  methods  of  computing  sizes  of  steam-mains  which  have 
been  given  allow  sufficiently  for  friction  for  cases  in  which  the 
pipes  are  not  of  considerable  length,  as  in  residence  heating  ; 
rbut  when  steam  must  be  carried  a  long  distance  more  satis- 
factory results  will  be  obtained  by  computing  the  capacity  from 
the  formula  given  in  Article  121,  page  218.  For  this  com- 
putation various  cases  can  be  considered  respecting  both 
steam-pressure  and  frictional  resistance.  The  following  tables 


*  "  Steam-heating  for  Buildings,"  Wm.  J.  Baldwin, 
f  Van  Nosirand's  Science  Series,  No.  68. 


226 


HEATING   AND    VENTILATING   BUILDINGS. 


INTERNAL   DIAMETERS   OF    STEAM-MAINS   FOR   A   SINGLE-PIPE 
SYSTEM   OF    HEATING    BY   DIRECT    RADIATION.* 

T Steam-pressure  10  Ibs.  above  atmosphere,  frictional  resistance  6  in.  of  water-column."! 

L  0.5      "  "  12    "      " 


Length  of  Steam-main  in  Feet. 

Radiating 
Surface, 

20 

40 

80 

IOO 

2OO 

300 

400 

600 

1000 

Sq.  Ft. 

Diameter  of  Pipe  in  Inches. 

20 

0-5 

0-5 

0.6 

0.6 

o.  7 

0.8 

0.8 

0.9 

I  .2 

40 

0.6 

0.7 

o.S 

0.8 

.0 

i  .0 

1.  1 

1.2 

1  .6 

60 

0.7 

0.8 

0.9 

I.O 

.  i 

1.2 

1-3 

1.4 

1,1 

80 

0.8 

0.9 

i  .0 

1.  1 

.2 

1.4 

1.5 

1.6 

2.  I 

100 

0.9 

I.O 

1.2 

1.2 

•4 

i  .  5 

1.6 

1-7 

2-3 

2OO 

.  i 

i-3 

1-5 

1.6 

.8 

1.9 

2.0 

2.2 

2-9 

300 

•  3 

1.8 

1.8 

2.  I 

2-3 

2.4 

2.6 

3-5 

400 

.5 

1-7 

2.0 

2.0 

2.4 

2.6 

2.7 

3-0 

4.0 

500 

.6 

1.9 

2.2 

2.2 

2.6 

2.8 

3-0 

3-2 

4-2 

600 

.8 

2.0 

2.4 

2-5 

2.8 

3.0 

3-2 

3-5 

4-5 

800 

2.0 

2-3 

2.6 

2.7 

3-2 

3.4 

3-6 

3-9 

5.0 

I.OOO 

2.2 

2  .  e, 

2.9 

3-0 

3.4 

3.7 

3-9 

4-3 

5-5 

1,400 

2-5 

2.8 

3-3 

3-4 

3.9 

4.2 

4-5 

4-9 

6-5 

1,  800 

2-7 

3-2 

3.6 

3.8 

4-4 

4.7 

5-0 

5-4 

7.0 

2.000 

2.9 

3-3 

3-8 

3-9 

4-5 

4.9 

5-2 

5.6 

7-2 

3,000 

3-4 

3-9 

4.4 

4.6 

5-3 

5-8 

6.1 

6.6 

3-5 

4,000 

3.8 

4-3 

5-0 

5-2 

6.0 

6.5 

6.8 

7-5 

9-7 

6,000 

4.1 

4-7 

5-4 

5.7 

6.5 

7-1 

7-4 

8.2 

10.5 

8,000 

4-4 

5-0 

5-8 

6.0 

7.0 

7-5 

7-9 

8.7 

"J 

10,000 

4-7 

5-3 

6.1 

6.4 

7-4 

8.0 

8.4 

9.2 

11.9 

*  The  table  is  computed  by  formulae  for  d,  page  218,  in  which  h  —  318.6, 
Q  =  9.2,  cu.  ft.  of  steam  per  minute  for  100  sq.  ft.  radiating  surface.  The 
table  is  computed  for  straight  pipes  with  water-level  in  returns  6  inches  above 
that  in  boiler.  In  case  there  are  bends  or  obstructions  consider  the  length  of 
pipe  increased  as  follows:  Right-angle  elbow  40  diameters;  globe-valve  125 
diameters;  entrance  to  tee  60  diameters,  For  other  resistances  and  steam- 
pressures  multiply  the  diameters  as  given  above  by  the  following  factors  : 

Water-level  in  return  above  boiler 2  in.         12  in.         18  in. 

Multiply  by 1.25         0.88  0.80 

Steam-pressure  above  atmosphere 0.5  Ibs.    2  Ibs.         5  Ibs. 

Multiply  by 1.22         1.16  1.09 

For  obtaining  the  diameter  of  steam-main  to  be  used  in  case  there  is  a 
separate  return  multiply  the  above  results  by  0.82. 

For  indirect  heating  without  separate  return  multiply  above  results  by  1.4, 
with  separate  return  use  the  results  in  the  form  given. 

Do  not  use  steam-pipe  less  than  ij  inches  in  diameter. 


DESIGN  OF  STEAM  AND   HOT-WATER   SYSTEMS.     226(1 


TABLE   FOR   THE   CAPACITY   OF   STEAM-PIPES    100   FEET  IN 
LENGTH  WITH  SEPARATE  RETURNS. 

By  A.  R.  WOLFF. 


2  Lbs.  Pressure. 

5  Lbs.  Pressure. 

Diameter  of 

Diameter  of 

Supply. 

Return. 

Inches. 

Inches. 

Total  Heat 
Transmitted. 

Radiating 
Surface. 

Total  Heat 
Transmitted. 

Radiating 
Surface. 

B.  T.  U. 

Square  Feet. 

B.  T.  U. 

Square  Feet. 

|  f 

I 

9000 

36 

15000 

60 

I* 

I 

18000 

72 

30000 

1  2O 

ri 

30000 

120 

50000 

200 

2 

ii 

70000 

280 

I2OOOO 

480 

2i 

2 

J32OOO 

528 

22OOOO 

880 

3' 

2i 

225000 

GOO 

375000 

1500 

3* 

2^ 

330000 

1320 

550000 

2200 

4 

3 

480000 

I92O 

800000 

3200 

4* 

3 

690000 

2760 

II50000 

4600 

5 

3* 

930000 

3720 

1550000 

6200 

6 

3* 

1500000 

6OOO 

25OOOOO 

IOOOO 

7 

4 

2250000 

9OOO 

3750000 

15000 

8 

4 

3200000 

12800 

5400000 

2I600 

9 

4* 

4450000 

17800 

7500000 

30000 

10 

5 

5800000 

23200 

9750000 

39000 

12 

6 

9250000 

37000 

15500000 

620(X> 

H 

7 

13500000 

54000 

23000000 

92000 

16 

8 

I9OOOOOO 

76000 

32500000 

130000 

In  above  table  each  square  foot  of  radiating  surface  is 
>umed  to  transmit  250  heat-units  per  hour,  a  safe  and  con- 
irvative  estimate,  as  will  be  seen  by  consulting  Chapter  IV. 
For  pipes  of  greater  length  than  100  feet  multiply  results 
the  above  table  by  the  square  root  of  100  divided  by  the 
length.  In  all  cases  the  length  is  to  be  taken  as  the  equivalent 
length  in  straight  pipe  of  the  pipe,  elbows,  and  valves,  as  given 
on  page  226.  For  other  lengths  multiply  above  results  by 
following  factors : 

Length  of  pipe  in  feet. .   200      300      400      500      600      700      800      900       1000 
Factor 0.71     0.58     0.5       0.45     0.41     0.38     0.35     0.33     0.32 

For  example,  the  capacity  of  a  pipe  8  inches  in  diameter 
and  800  feet  long  would  be  0.35  of  12800  sq.  ft.  of  radiating 
surface  =  4480  sq.  ft.  It  will  be  noted  that  the  size  of  return 
specified  by  Mr.  Wolff  is  about  one  pipe-size  greater  than  be- 
lieved to  be  necessary  by  the  author,  but  sizes  of  main  steam- 
pipe  are  in  substantial  agreement  with  tables  on  pp.  226and  226^. 


226b        HEATING   AND    VENTILATING   BUILDINGS. 

The  following  table  will  be  found  convenient  for  obtaining 
the  size  of  a  steam-main  for  low-pressure  steam-heating,  single- 
pipe  system,  for  various  lengths.  The  table  is  computed  from 
same  formulae  as  those  on  page  226,  but  for  a  lower  steam- 
pressure,  and  results  are  given  in  commercial  sizes  of  pipes. 


COMMERCIAL   SIZES    OF   STEAM-MAINS    FOR   A   SINGLE    PIPE. 

(System  of  heating  by  direct  radiation;  pressure  0.5  Ibs.;  friction  resistance  6  inches  of  water 
for  lengths  100  feet  and  under,  12  inches  of  water  for  greater  distances.) 


Length  of  Steam-main  in  Feet. 


Radiating 
Surface. 

80 

Square  Feet. 

20 

40 

IOO 

200 

300 

400 

600 

IOOO 

Diameter  of  Pipe  in  Inches 

20 

I 

i 

l\ 

,. 

j! 

i 

* 

40 

!i 

ii 

i- 

Ti 

-  • 

I- 

t| 

4 

60 
80 
IOO 

Jl 

ii 
ii 

i- 
i- 

I* 

I- 
t] 

if 

4 

2 
2 

200 

ij 

i4 

2 

2 

2 

2 

2 

2: 

3 

300 

2 

2 

2 

2 

2 

"•' 

2^ 

3 

3j 

400 

2 

2 

24 

24 

24 

3 

3 

3 

4 

500 

2 

24 

24 

3 

3 

3 

3* 

3* 

4 

600 

24 

24 

3 

3 

34 

3 

3 

3 

4* 

800 

24 

3 

34 

34 

3l5 

3i 

4 

4 

5" 

IOOO 

3 

34 

4 

4 

4 

4 

6 

1400 

34 

34 

4 

4 

4 

4? 

4* 

5 

6 

1800 

4 

4 

4 

4 

4l? 

5 

5 

6 

7 

2OOO 

4 

4 

4 

44 

4i 

5 

5 

6 

7 

3000 

44 

44 

44 

5 

5 

6 

6 

7 

8 

4OOO 

5 

5 

5 

6 

6 

7 

7 

7 

9 

6000 

54 

54 

6 

7 

7 

7 

'  7 

8 

10 

8000 

54 

6 

7 

7 

8 

8 

9 

ii 

1OOOO 

6 

6 

6 

7 

8 

8 

9 

10 

12 

I20CO 

6 

7 

7 

•7 

8 

8 

10 

II              12 

I4OOO 

7 

7 

7 

8 

9 

9 

10 

12              14 

16000 

7 

8 

8 

9 

9 

10 

ii 

12 

14 

18000 

8 

8 

8 

9 

10 

ii 

ii 

12 

M 

2OOOO 

9 

9 

9 

10 

ii 

ii 

12 

14 

16 

In    using   the   above   table    take   the   equivalent   length    as  explained    on 
page  226. 


DESIGN  OF  STEAM  AND    HOT-WATER   SYSTEMS.     22? 

for  capacity  of  steam-mains  are  computed  for  steam  10  pounds 
above  atmospheric  pressure,  and  the  frictional  resistance  6 
inches  of  water  column.  Tables  computed  from  the  same 
formula  and  covering  other  conditions  will  be  found  in 
44  Steam-heating,"  *  by  Robert  Briggs,  and  can  be  consulted 
when  desired. 

123.  Size  of  Return-pipes,  Steam-heating.— The  size 
fcof  return-pipes,  if  figured  from  the  actual  volume  of  water  to 
zbe  carried  back,  would  be  smaller  than  is  safe  to  use,  largely 
because  of  air  which  is  contained  in  the  steam-pipes,  and  which 
odoes  not  change  in  volume  when  the  steam  is  condensed.  For 
this  reason  it  is  necessary  to  use  dimensions  which  have  been 
proved  by  practical  experience  to  be  satisfactory.  When  the 
steam-main  is  large,  the  diameter  of  the  return-pipe  will 
Jprove  satisfactory  if  taken  one  size  less  than  one  half  that  of 
the  steam-pipe ;  but  if  the  steam-main  is  small,  for  instance, 
,5  inches  or  less,  the  return-pipe  should  be  but  one  or  two  sizes 
smaller.  The  return-pipe  should  never  be  less  than  I  inch,  in 
-order  to  give  satisfactory  results.  The  following  table  suggests 
sizes  of  returns  which  will  prove  satisfactory  for  sizes  of  main 
steam-pipes  as  given  : 


Diameter 
Steam-pipe. 

Diameter 
Return-pipe. 

Diameter 
Steam-  pipe. 

Diameter 
Return-pipe. 

inches. 

inches. 

inches. 

inches. 

2 

if 

5 
6 

3 

3 

3l 

2 

8 

9 
10 

4 

4i 
4i 

4 

2± 

12 

5 

The  size  of  return-pipes,  if  computed  on  basis  of  reduction 
in  volume  due  to  condensation  of  the  steam,  supposing  the 
steam  to  have  a  gauge-pressure  of  40  pounds  and  that  one  half 
its  volume  is  air,  would  be,  neglecting  friction,  about  one  sixth 
of  that  of  the  main  steam-pipe,  which  is  much  smaller  than 
would  be  considered  safe  in  practice. 


*  Van  Nostrand's  Science  Series,  No.  68. 


228 


HEATING   AND    VENTILATING   BUILDINGS. 


Main  and  Return-pipes  for  Indirect  Heating  Surfaces. — The 
indirect  heating  surfaces  require  about  twice  as  much  heat  as  the 
same  quantity  of  direct  radiating  surface,  and  hence,  for  same  re- 
sistance in  the  pipe,  the  area  should  be  twice  that  required  in  di- 
rect heating.  It  will  usually  be  sufficiently  accurate  to  use  a  pipe3 
whose  diameter  is  1.4  times  greater  than  that  for  direct  heating. 

Reliefs  and  Drip-pipes. — The  size  of  drip-pipes  necessary  to 
convey  the  water  of   condensation    from   a   main  steam  to  a 
return   cannot  be  obtained  by  computation,  as  there  is  much 
uncertainty  regarding    the    amount    of   water   that   will   flowl 
through. 

As  the  flow  through  the  relief  tends  to  increase  the  press- 
ure in  the  return,  it  may  also  serve  to  lessen  the  velocity  of 
flow  beyond  the  point  of  junction,  provided  the  size  is  greater 
than  necessary  to  carry  off  the  water  of  condensation  from  the 
steam-main.  Drip-pipes  should  be  united  to  the  return  in 
such  a  manner  as  to  re-enforce  rather  than  impede  the  circula-i 
tion,  which  result  can  usually  be  attained  by  joining  the  pipes 
with  60  or  45  degree  fittings. 

The  writer  would  recommend  the  employment  of  the  fol- 
lowing sizes  of  drip-pipes  as  ample  for  usual  conditions  : 


DIAMETER   OF    DRIP-PIPE   FOR    STEAM-MAINS   OF   VARIOUS 

LENGTHS. 


Length  of  Steam-main  in  Feet. 

Diameter 

of 
Steam-main, 

o  to  100. 

IOO  tO  2OO. 

2OO  tO  4OQ. 

4XX3  to  600. 

Inches. 

Diameter  of  Drip-pipe  in  Inches. 

OtO  2 

| 

\ 

1 

I 

3 

i 

f 

i 

i 

4 

f 

f 

i 

i^ 

5 

f 

if 

i^. 

6 

I 

I* 

i* 

i* 

124.  Size  of  Pipes  for  Hot-water  Radiators.— Method 
of  computation  of  the  velocity  with  which  circulation  will  take 
place  in  a  hot-water  heating-system  without  friction  has  been 
considered  in  Article  121,  page  220.  In  some  instances  this 


DESIGN  OF  STEAM  AND    HOT-WATER   SYSTEMS. 

velocity  is  increased  by  bubbles  or  particles  of  steam  which 
pass  up  the  main  risers  and  reduce  the  specific  gravity  of  the 
water  in  the  ascending  pipes  to  such  an  extent  that  the  actual 
velocity  produced  is  much  in  excess  of  what  would  have  been 
possible  had  no  steam  formed.  This  condition  is  undesirable, 
as  it  is  usually  accompanied  with  more  or  less  noise  and  a  very 
high  temperature  in  the  boiler,  and  should  not  serve  as  a  basis 
for  designing  main-pipes  to  be  used  in  hot-water  heating  ap- 
paratus. It  should  not  be  recommended  that  heaters  be  run  in 
[such  a  manner  as  to  produce  steam  in  any  part  of  the  circulation. 

The  heat  which  is  given  off  from  radiating  surfaces  of  va- 
rious kinds  has  already  been  considered  (page  204),  and  as  each 
thermal  unit  given  off  by  the  surface  is  obtained  by  the  cooling 
•of  one  pound  of  water  one  degree  in  temperature,  it  is  easy 
;to  compute  from  the  data  already  given  (i)  the  weight  of 
hvater  required,  and  (2)  the  number  of  cubic  feet  needed  to 
peat  each  square  foot  of  radiating  surface. 

The  following  table  gives  the  data  necessary  for  computing 
[the  volume  of  water  required  to  supply  radiating  surface  for 
various  conditions  likely  to  occur  in  heating  : 

HOT-WATER    HEATING. 
DATA  USED  IN  COMPUTATION  OF  TABLES. 

Temperature  outside  air o  o  o  o  o 

Temperature  water  in  radiator. .  140  160  180  200  220 
:  Heat-units  per  degree  diff.  tem- 
perature per  square  foot  per 

hour 1.4  1.45  1.5  1.6  1.8 

.Weight  of  cu.  ft.  water,  pounds..  61.37  60.98  60.55  60.07  59-64 
Total  heat-units  per.square  foot 
per  hour : 

Room  60°  per  sq.  ft 113  145  180  224  288 

70°    "     "    " 98  130  165  208  270 

Cubic  feet  of  water  required  to 

supply  one  sq,  ft.  per  hour. 

Radiator  cooled   5° — Room  70°  0.316  0.426  0.546  O.6S6  0.902 

60°  0.396  0.472  0.592  0.740  0.970 

70°  0.158  0.213  0.273  0.343  0.451 

60°  0.183  0.236  0.296  0.37  0.483 

70°  0.138  0.142  0.182  0.228  0.339 

60°  0.132  0.157  0.131  0.247  0.361 

70°  0.079  0.107  0.137  0.172  0.226 

60°  0.091  0.118  0.148  0.175  0.241 

By  dividing  the  number  of  cubic  feet  to  be  supplied  per 
hour  by  the  velocity  with  which  the  water  moves  per  hour  we 
obtain  the  area  of  the  pipe  in  square  feet. 


Radiator  cooled  10° — 
«  « 

Radiator  cooled  15° — 
Radiator  cooled  20° — 


230  HEATING   AND    VENTILATING   BUILDINGS. 

The  general  case  from  which  practical  tables  may  be  com- 
puted can  best  be  considered  by  the  use  of  formulae,  as  fol- 
lows : 

Let  w  equal  the  weight  of  water  per  cubic  foot,  let  H  equal  total 
heat  per  square  foot  per  hour  from  radiator,  R  total  radiating  surface,  Q 
number  of  cubic  feet  of  water  per  hour,  A  area  of  pipe  in  square  feet,  a 
area  of  pipe  in  square  inches,  u  velocity  in  feet  per  second  as  given  in 
table,  page  221,  V equal  velocity  in  feet  per  hour,  TMossof  temperature  ofj 
•water  in  radiator.  We  have  the  following  formulae: 


(1)  a. 

(2)  V 

,     HR i  Total  heat  divided  by  heat  given  off  by  i 

^-     wT~y\  cu.  ft.  equals  total  number  of  cubic  feet. 

O          0  a        _ 

which 


(5)     Q  =  2$av.     Equate  (3)  and  (5),  and 


HR 


By  taking  special  values  corresponding  to  temperatures  of  water  and 
of  surrounding  air  we  can  reduce  these  formulae  to  simple  forms.  Thus, 
if  the  temperature  of  the  radiator  is  180°  and  of  the  room  70°,  the  total  _ 
heat-units  given  off  per  hour,  H,  will  be  165.  If  we  further  assume  that 
the  water  in  the  radiator  cools  during  the  circulation  a  certain  amount, 
say  10  degrees,  T  will  equal  10,  weight  of  water  w  will  equal  60.5  pounds, 
and  we  shall  have  formulae  8  and  9  : 

(8)  R  = 

>> 

(9)  *= 


For  the  above  condition  the  radiating  surface  is  equal  to 
92  times  the  area  of  the  main  pipe  in  square  inches  times  the 
velocity  of  the  water  in  feet  per  second  ;  and  further,  the  area 
in  square  inches  is  equal  to  the  radiating  surface  divided  by 
92  times  the  velocity.  The  velocity  in  feet  per  second  will 
depend  upon  the  height,  the  difference  of  temperature,  and 
amount  of  friction. 

The  following  table  gives  relations  of  radiating  surfaces  to 
areas  of  main  pipes,  friction  neglected.  For  distances  less 
than  200  ft.  sufficient  allowance  for  friction  will  be  made  by 
making  the  main  one  size  larger  than  required  by  table. 


DESIGN   OF  STEAM  AND   HOT-WATER   SYSTEMS. 


AREA   AND    DIAMETER  OF  HOT-WATER  HEATING-MAIN, 
DIRECT    RADIATION.* 

DIFFERENCE  OF  TEMPERATURE,  10  DEGREES. 


(1) 

(2) 

(3) 

(4) 

(5) 

Height, 

Feet. 

Velocity  Water 
Feet  per  Second. 

Multiply  each 
ioo  Square  Feet 
Radiating  Surface 
for  Area  Main  by 

Multiply  Square 
Root  Radiating 
Surface  for 
Diameter  by 

Equivalent  Head 
in  Feet. 

I 

0-335 

3-26 

0.205 

0.0015 

5 

0.750 

1-45 

0.133 

O.ooSl 

10 

1.  06 

1.03 

0.113 

0.017 

15 

1.28 

0.85 

o.  104 

0.025 

20 

15 

0.723 

0.095 

o  035 

25 

1.67 

0.65 

O.ogi 

0.044 

30 

1.83 

0-595 

0.087 

0.052 

40 

2.12 

0.513 

0.081 

0.072 

50 

2-37 

0.46 

0.076 

0.088 

60- 

2-59 

0.42 

0.072 

o.  105 

80 

3-00 

0.362 

0.068 

0.142 

100 

3-35 

0.324 

0.064 

0.176 

In  the  above  table  column  (i)  gives  the  height  in  feet  ; 
column  (2)  the  velocity  corresponding  to  the  head  for  a  reduc- 
tion in  temperature  of  10°  F.;  column  (3)  is  the  area  in  square 
inches,  neglecting  friction,  for  each  ioo  square  feet  of  radiating 
surface  ;  column  (4)  is  the  corresponding  diameter  of  pipe 
required  for  each  square  foot  of  surface,  and  is  to  be  multiplied 
by  the  number  of  square  feet  of  radiating  surface  to  give  the 
diameter  for  any  given  case  ;  the  actual  diameter  should  be  one 
pipe  size  greater ;  column  (5)  is  the  equivalent  head  which 
would  produce  the  same  velocity  if  falling  freely  in  the  air. 

The  preceding  table  is  in  the  same  form  as  that  given  for 
diameters  of  steam-main.  If  we  consider  10  feet  as  the  aver- 
age height  or  head  producing  circulation  for  the  first  floor,  it 
will  be  seen  that  we  shall  need,  neglecting  friction,  one  square 
inch  in  area  in  our  main  pipe  for  each  ioo  square  feet  of  radia- 
tion, or  the  diameter  of  our  pipe  would  be  found  for  this  case 

*  As  illustrating  the  use  of  the  table,  compute  the  area  of  main  pipe  needed 
to  supply  350  square  feet  of  direct  radiation  situated  25  feet  above  the  heater. 
The  area  is  obtained  by  multiplying  3.5  by  0.65,  which  will  equal  2.28  square 
inches.  The  diameter  can  be  found  from  this,  or  it  may  be  obtained  from 
column  (4),  by  multiplying  the  square  root  of  350  by  0.091.  The  square  root  of 
350  is  18.7,  the  product  is  1.7.  The  pipe  used,  if  the  distance  is  about  200  feet, 
should  be  i\  inches  in  diameter. 


232  HEATING   AND    VENTILATING   BUILDINGS. 

as  equal  approximately  to  \  of  the  square  root  of  the  radiating 
surface  in  square  feet. 

If  the  temperature  of  the  water  be  supposed  to  change  20°  in 
passing  through  the  radiators,the  required  area  of  the  main  would 
be  one  half  of  that  given  by  the  table  ;  if  15°,  two  thirds,  etc. 

In  hot-water  heating  the  return-pipe  must  have  the  same 
diameter  as  the  supply-pipe,  since  there  is  no  sensible  change 
in  bulk  between  the  hot  and  cold  water. 

We  may  take  as  a  practical  rule,  applicable  when  less  than 
200  feet  in  length  :  The  diameter  of  main  supply-  or  return-pipe 
in  a  system  of  direct  hot-water  heating  should  be  one  pipe-size 
greater  than  the  square  root  of  the  number  of  square  feet  of  radiat- 
ing surface  divided  by  9  for  the  first  story,  by  10  for  tJie  second 
story,  and  by  1 1  for  the  third  story  of  a  building ;  for  indirect 
hot-water  multiply  above  results  by  1.5. 

125.  Size  of  Ducts  and  Ventilating-flue  for  Conveying 
Air. — The  method  of  computing  the  sizes  of  flues  would  evi- 
dently be  that  of  dividing  the  total  amount  of  air  which  is 
required  in  a  given  time  by  that  delivered  or  discharged  through 
a  flue  one  square  foot  in  area.  A  table  has  been  given  for: 
cubic  feet  of  air  delivered  in  ventilating-pipes,  see  Chapter  I, 
pages  45  to  52.  The  air  required  can  be  found  as  explained 
in  Article  119,  page  211,  formula  4,  or  by  consulting  the  table, 
page  213,  which  gives  the  factors  to  be  multiplied  by  the  area 
of  glass  plus  J  the  exposed  wall  surface  when  the  air  enters  at 
various  temperatures  above  that  in  the  room. 

As  an  illustration,  consider  the  same  problem  as  in  previous 
cases,  viz.,  that  of  a  room  with  48  square  feet  of  glass  surface 
and  320  square  feet  of  exposed  wall  surface,  and  from  which 
the  heat  loss  per  degree  difference  of  temperature  is  128. 
Supposing  air  in  room  to  be  70°  F.  and  that  supplied  by  flue  to 
be  100°  F.,  we  see  by  table  page  213,  that  for  every  heat-unit 
as  above  there  will  be  required  135  cubic  feet  of  air  per  hour, 
and  for  this  case  we  will  require  135  X  128  =  17,280  cubic  feet 
per  hour.  If  excess  of  temperature  of  air  in  flue  over  that 
outside  be  considered  as  50°,  and  height  of  flue  as  10  feet,  the 
discharge  per  square  foot  of  flue  (see  table  page  45)  will  be  242 
feet  per  minute,  or  14,520  per  hour.  Hence  the  required  area 
of  the  flue  will  be  17,280  divided  by  14,520=  1.19  square  feet 


DESIGN  OF  STEAM  AND   HOT-WATER   SYSTEMS.     233 

=  171  square  inches.      In  a  similar  manner  areas  of  flues  may 
be  computed  for  any  given  case. 

As  the  velocity  of  flow  increases  with  difference  of  tem- 
perature between  outside  air  and  that  in  the  flue,  and  is  les- 
sened when  this  difference  is  small,  it  is  better  to  assume  a 
mean  difference  of  temperature  so  low  that  the  computation 
will  certainly  afford  plenty  of  air  for  ventilation. 

AREA    OF    FLUE    IN    SQUARE    INCHES    REQUIRED   TO   SUPPLY 
GIVEN   AMOUNT   OF    HEAT. 

(Excess  of  temperature  is  30°  ;  allowance  for  friction  5056.) 


Height  or  Head  of  Flue  in  Feet. 


Z    is* 


5 

IO 

15 

20 

30 

40 

50 

60 

80 

IOO 

H    — 

Area  of  Flue  in  Square  Inches. 

B.T.U. 

B.  T.  U. 

j 

700 

IO 

24 

17 

14 

II 

9.2'   8.2 

7-1 

6.6 

6.1  5.5 

1400 

20 

48 

35 

28 

22 

18.4  16.4 

13-2 

12.2  10.9 

2IOO 

30 

72 

52 

42 

33 

28   25 

21 

19-5 

I8.3JI6.3 

28OO 

40 

96 

69 

56 

44 

37 

33 

28 

26 

24.421.8 

3500 

50 

120 

87 

71 

55 

46 

41 

35 

32.6 

30  .  5  j  2  7  .  3 

525O 

75 

1  80 

129 

116 

82 

69 

61 

53 

48 

45.740.8 

7OOO 

IOO 

240 

173 

141 

109 

93 

82 

71 

66 

61   54-5 

8/50 

125 

300 

216 

176 

136 

115 

102 

87 

82 

76.568.1 

10500 

150 

360 

258 

212 

164 

138 

122 

105 

98 

I52l8i.7 

12250:    175 

420 

302 

247 

191 

162   143 

123 

114 

10795.3 

14000 

200 

480 

346 

244 

218 

184 

!63 

141 

130 

124  109 

17500 

250 

600 

432 

315 

273 

231 

204 

175 

163 

153  136 

2ICOO 

300 

720 

519 

423 

327 

278 

245 

211 

195 

183  163 

2SOOO 

400 

960 

652 

564 

436 

369 

327 

28l 

261 

244  218 

35000    500 

1200 

865 

715 

545 

462 

408 

352 

326 

306  273 

52500 

750 

1  800 

1290 

IO6O 

825 

693 

612 

527 

457 

458  408 

7OOOO 

1000 

24OO 

1730 

I41O 

1090 

925 

818 

705 

655 

612)  545 

87500 

1250 

3OOO 

2160 

1760 

1360  §150  ;loi8 

870 

820  7651  681 

IO5OOO 

1500 

3600 

2580 

2120 

1640 

1380   1218 

1055 

980,1520:  817 

I4OOOO 

2000 

4800 

3460 

2440 

2  1  SO 

1840 

1630 

I4IO 

1300  1240  1090 

i75oooj  2500 

6OOO 

4320 

3150 

2730 

2310  ,2040 

»750 

1630  1530:1360 

2IOOOO 

3000 

7200 

5190 

4230 

3270 

2780   2450 

2I1O 

1950'  1  830!  1630 

Table  is  computed  by  finding  air  required  to  supply  heat  by  formula  4, 
page  211,  when  outside  air  is  o°,  inside  air  70%  and  heated  air  100°,  and  dividing 
this  by  the  air  supplied  by  a  flue  one  square  foot  in  area  for  the  given  height 
and  a  difference  of  temperature  of  30°,  as  obtained  in  table  page  45.  Ventilat- 
ing flues  for  a  given  height  should  be  taken  one  quarter  larger  than  the  values 
given  in  the  table.  See  note  on  page  246. 

*  See  page  57. 

f  Approximately  equal  to  area  of  glass  plus  one  fourth  the  exposed  wall- 
surface.  See  page  59. 


234 


HEATING   AND    VENTILATING   BUILDINGS. 


The  table  on  p.  233  is  computed  by  the  method  explained 
for  different  heights  of  flue  and  for  a  difference  of  temperature 
of  the  air  in  the  flue  over  that  in  the  space  into  which  it 
discharges  of  30°  F. 

For  difference  of  temperature  other  than  30°  multiply 
results  in  the  table  by  the  following  factors  to  obtain  the  area 
of  the  flue  : 


Difference 
Temperature, 
Degrees. 

Factor. 

Difference 
Temperature, 
Degrees. 

Factor. 

IO 
2O 
40 

1-74 
1.22 
0.87 

50 
60 
70 

0-775 
0.71 
0.655 

For  usual  conditions  of  residence  heating  in  which  the  air 
in  the  supply-flue  is  30°  above  the  temperature  of  the  air  in: 
the  room,  and  that  in  the  ventilating-flue  20°,  we  may  compute 
the  approximate  area  in  square  inches  of  the  supply-  and  venti-^ 
lating-duct,  by  multiplying  each  heat-unit  per  degree  difference 
of  temperature  lost  from  the  walls  by  a  series  of  simple  factors, 
which  are  easily  memorized. 

TABLE  OF  FACTORS  FOR  AREA  OF  AIR-FLUES. 


suppiy-auct 

ve 

ntnating-au 

:t. 

Story  of  Building. 

Approxi- 
mate 
Head  in 
feet. 

Velocity 
in  feet 
per  sec. 

Factor  for 
Area, 
sq.  in. 

Approxi- 
mate 
Distance 
to  Roof. 

Velocity 
in  feet 
per  sec. 

Factor  for 
Area, 
sq.  in. 

First  Floor  
Second    " 

(1) 

5 
28 

(2) 
2.8 

6  8 

(3) 
2.40 

(4) 
47 

(5) 

5-5 

(6) 
O.Q3 

Third      " 

JO 

8   i 

o  82 

j"4 
20 

o  6 

Fourth    "    

50 

9- 

0.71 

IO 

2.6 

2.17 

As  an  example,  find  the  required  area  of  heat-  and  venti- 
lating-ducts  for  a  room  with  200  square  feet  of  exposed  wall- 
surface  and  30  square  feet  of  glass  :  30  plus  one  fourth  of  200 
is  80,  the  approximate  building  loss  per  degree.  This  quantity 
multiplied  by  factors  in  columns  (3)  and  (5)  gives  respective 
areas  of  flues  in  square  inches  with  sufficient  exactness  for 
ordinary  requirements.  The  factors  afford  a  ready  means  of 
computation  in  the  absence  of  an  extended  table,  similar  to 
that  on  page  233. 


DESIGN  OF  STEAM  AND    HOT-WATER   SYSTEMS.     235 

In  some  instances  the  amount  of  air  can  be  computed  as 
a  function  of  the  cubic  contents  of  the  room,  especially  when 
required  for  ventilation  alone.  For  ventilation  purposes  the 
problem  of  proportioning  the  air-passages  is  solved  simply  by 
computing,  first,  the  air  required,  on  the  basis  of  1800  cubic  feet 
per  hour  for  each  person  who  will  occupy  the  room ;  second, 
-the  number  of  times  the  air  will  be  changed  per  hour,  by 
dividing  this  result  by  the  volume  of  the  room.  This  method 
is  considered  fully  in  Article  38,  page  53,  and  a  table  is  given 
for  computing  the  area  of  the  flue  in  square  inches  for  different 
velocities  of  the  moving  air. 

In  applying  this  method  to  practical  problems,  it  is  best  to 
^proportion  the  ducts  so  that  in  no  case  will  the  required 
^velocity  of  the  air  in  the  flue  exceed  12  feet  per  second  or 
43,200  feet  per  hour,  an  amount  not  likely  to  be  reached 
without  a  fan  or  blower,  and  one  which  corresponds  to  a 
'pressure  of  nearly  o.i  inch  of  water  (pages  42  to  53). 

126.  Dimensions  of  Registers. — The  registers  should  be 
so  proportioned  that  the  velocity  of  the  entering  air  will  not 
be  sufficient  to  produce  a  sensible  draft  ;  that  is,  the  area  must 
pe  such  that  the  velocity  shall  not  exceed  3  to  5  feet  per 
second  or  10,800  to  18,000  lineal  feet  per  hour.  The  writer 
thinks  that  very  excellent  results  are  obtained  by  proportion- 
ing the  registers*  for  first  floor  so  as  to  give  velocity  of  2^ 
feet  per  second,  and  those  of  higher  floors  and  at  entrance  to 
ventilating-shafts  3  feet  per  second.*  The  results  above,  ex- 
Pcept  for  entrances  to  ventilating-shafts  on  the  top  floor,  are 
less  than  is  usually  produced  by  natural  draft,  so  that  the  area 
computed  by  dividing  the  total  amount  of  air  required  by  the 
number  which  expresses  the  velocity  gives  satisfactory  results. 

The  above  rules  are  for  effective  or  clear  opening,  and  this 
will  be  found  in  each  case  to  be  about  two  thirds  of  the  nomi- 
;nal  or  rated  size  of  the  register  as  shown  in  the  table  given  in 
Article  144. 

By  computing,  from  the  data  given,  the  number  of  changes 
?of  air  per  hour  in  room,  the  table  page  53  can  be  used  as 
explained  to  determine  the  effective  area  in  square  inches 
required  for  each  1000  cubic  feet  of  space. 

*  See  page  52,  Article  38. 


236  HEATING   AND    VENTILATING   BUILDINGS. 

As  an  example  illustrating  use  of  this  table,  suppose,  in  a 
room  containing  2500  cubic  feet,  air  to  be  changed  four  times\ 
per  hour,  and  that  velocity  in  air-flue  be  6  feet  per  second,  in 
ventilating-shaft  4  feet,  through  fresh-air  register  2.5  feet, 
through  ventilating-register  3  feet. 

The  table  on   page   53   gives  the  net  area  for  each    IOOO' 
cubic  feet  of  space,  so  that  for  above  conditions  the  results  as 
found  in  the  table  must  be  multiplied  by  2.5.     We  should  have, 
taking  2.5  times  the  tabulated  values,  the  following  results : 

Net  area  supply-flue  67.5  sq.  in.;  ventilating-shaft  100  sq.  in.; 
fresh-air  register  166  sq.  in.;  ventilating-register  136.5  sq.  in. 

The  nominal  area  of  the  register  to  be  used  should  be  about 
50   per   cent    greater   than    the    net    area ;    it  may   be    taken- 
from  the  table  given  in  Article  144.     The  velocity  correspond-? 
ing  to  2.5  feet  per  second  is  taken  as  the  mean  of  that  given., 
in  the  table  for  2  and  3. 

It  is  best  to  make  flue  dimensions  about  one  inch  greater! 
than  obtained  by  calculation,  to  allow  for  surface  friction. 

127.  Summary  of  Various  Methods  of  Computing  Quan- 
tities   Required    for   Heating. — The   following    table  giveJ 
the  required  size  of  steam-pipes  and  of  steam-boiler  or  hot-watefl 
heater,  for  various  amounts  of  radiating  surface.     The  proporl 
tions  given  will  apply  to  residence  heating  or  where  the  length 
of  main  pipe  is  not  over  200  feet.     The   value   given   for  the 
steam-main  is  that  for  the  single-pipe  system  when  no  return 
is  needed.     For  the  system  of  separate  steam-  and  return-pipes? 
the  diameter  of  the  steam-main  should  be  taken  f  of  that  givenl 
that  of   the   return    as  in  table   page  227.     The   cubic   spaed 
heated  is  given  if  the  ratio  to  radiating  surface  be  known  ;  this$ 
is  an  approximation  only,  although   it  may  often  serve   a  use*: 
ful  purpose  when  experience  has  been  gained  of  heat  required^ 
in  constructions  of  similar  nature  in  the  same  locality. 

About  two  thirds  as  much  air  is  warmed  by  hot-water  as 
by  steam  radiators,  and  flues  should  be  about  two  thirds  as  large! 
as  given  in  the  table  on  page  238. 

128.  Heating  of  Greenhouses.— Greenhouses    and    con- 
servatories are  heated  in  some  cases  by  steam  and  in  othea 
cases  by  hot  water,  and  there  is  quite  a  difference  of  opinion! 
held   by  florists   respecting   the   relative   merits   of  these  tw<j 


DESIGN  OF  STEAM  AND   HOT- WATER   SYSTEMS.     237 


o'     «-         ooo 

1         M                                   O     O     ""> 

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::::;::: 

:::«::::: 

li 

K 

^ 

Radiating  surface,  square  feet  
Diameter  steam-main,  inches*..  . 
Heating-surface  boiler,  square  feet 
Grate-area  boiler,  square  feet  
Diameter  smoke-flue,  inches  
Cubic  feet  heated,  40  to  i  
50  to  i  
7$toi  

Radiating  surlace,  square  feet  
Diameter  pipe,  inches  ist  story*... 
2d  story  
"  3d  siory  
Heating-surface  heater,  square  feet 
Grate-area  heater,  square  feet.  .  
Diameter  smoke-flue,  inches  
Cubic  feet  heated,  20  to  i  
30  to  i  
40  to  i  

Square  feet  radiation  
Cubic  leet  air  heated  per  minute.. 
Diameter  main  steam-pipe*  
Heating-surface  boiler,  square  feet 
Grate-area  boiler,  square  feet  
Diameter  smoke-flue,  inches  
Cubic  feet  heated,  20  to  i  
30  to  i  
40  to  i  

Square  feet  radiation  
Cubic  feet  air  heated  per  minute.  . 
Diameter  supply-  and  return-pipe*. 
Heating-surface  in  boiler,  square  fe 
Grate-area  in  boiler,  square  feet  .  . 
Diameter  smoke  flue,  inches  
Cubic  feet  heated,  15101  
"  25  to  i  
35  to  i  

o 

OS 

o 

b. 

1 

238  HEATING   AND    VENTILATING    BUILDINGS. 

HOT-AIR    AND  VENTILATING    FLUES. 
INDIRECT  RADIATION  STEAM  CIRCULATION. 


Square  feet  radiation   

2C 

CQ 

7c 

IOO 

12Z 

I^O 

17  = 

2OO 

2«O 

Cubic  feet  air  per  minute               . 

122 

244 

062 

j86 

f)O2 

72Q 

846 

Q72 

I22O 

Area  hot-air  flue,  square  feet  : 
1st  story 

O    72 

I    4^ 

2    16 

2    87 

o    cT 

4q 

c    o 

57 

7    ^ 

2d  story   

O    2Q 

O    <^Q 

o  88 

I    Q 

I    47 

I     78 

2    06 

2    7^ 

2    CK 

qd  story  .  . 

O    2.1 

O   4Q 

O    7i 

O   Q7 

I    22 

I    46 

1    7 

I    Q^ 

2.4^ 

Area  ventilating  flue,  square  feet  : 
1st  story        .        

O    ^7 

O    74 

j    j 

I    46 

I    8l 

2    2 

2    ^1 

2    Q^ 

a    7 

2d  story  .    

o  48 

0   87 

I    44 

I    Q2 

2    -37 

2.8 

-3  .  -2C 

-}    84 

4  8 

3d  story 

Oe  c 

j    j 

I    64 

2    2 

2    71 

3<3 

•*      8^ 

4        A 

5j 

Actual  area  register,  square  feet  : 

I    22 

2    4 

^  6 

1   Q 

6 

7  .  ^ 

8   4 

Q.  7 

12  .2 

2d  and  above 

I    O 

2 

0 

6 

7 

8  o 

IO   O 

Ventilating  register,  square  feet.  .  . 

0.6 

1.2 

1.8 

2.4 

3 

3-6 

4.2 

4.8 

6.1 

methods  of  heating.  The  fact,  however,  that  either  system 
when  properly  proportioned  and  well  constructed  gives  satisfac- 
tory results  indicates  that  the  difference  is  not  great,  and  that 
the  relative  value  may  depend  entirely  on  local  conditions. 

The  methods  of  piping  employed  may  in  a  general  way  be 
like  those  described,  and  the  pipes  may  be  located  so  as  to  run 
underneath  the  beds  of  growing  plants,  or  in  the  air  above,  as 
bottom  or  top  heat  is  preferred.  In  many  cases  large  cast-iron 
pipes,  the  method  of  erection  of  which  is  described  in  Article  58, 
page  88,  are  used  in  hot-water  heating  of  greenhouses,  These 
are  generally  located  beneath  the  beds  of  growing  plants  ;  the 
main  flow-  and  return-pipes  are  laid  in  parallel  lines,  with  an  up- 
ward pitch  from  the  boiler  to  the  farthest  extremity  of  the 
house.  Recently  small  wrought-iron  pipes,  Article  59,  page 
89,  have  been  used  extensively  for  greenhouse  heating.  In 
this  case  the  main  pipe  has  generally  been  run  near  the  upper 
part  of  the  greenhouse  and  to  the  farthest  extremity  in  one  or 
more  branches,  with  a  pitch  upward  from  the  heater  for  hot- 
water  heating  and  with  a  pitch  downward  for  steam-heating. 
The  principal  radiating  surface  is  made  of  parallel  lines  of 
i^-inch,  or  larger,  pipe,  placed  under  the  benches  and  sup- 
plied by  the  return  current;  this  has  in  all  cases  a  pitch  toward 
the  heater.  An  illustration  of  the  method  of  piping  as  de- 
signed by  A.  H.  Dudley  of  the  Herendeen  Mfg.  Co.  is  shown 
in  Figs.  193,  194,  and  195  so  clearly  as  to  require  no  special 
explanation. 


DESIG-N  OF  STEAM  AND   HOT-WATER   SYSTEMS.     239 


Any  system  of  piping  which  gives  free  circulation  and 
which  is  adapted  to  the  local  conditions  will  give  satisfactory 
results.  The  directions  for  erecting  and  taking  off  branches  are 
the  same  as  in  residence  heating  (see  page  191). 

Proportioning  Radiating  Surface.  —  The  loss  of  heat  from  a 
greenhouse  or  conservatory  is  due  principally  to  the  extent  of 
glass  surface  ;  hence  the  amount  of  radiating  surface  is  to  be 


FIG.  193. — PLAN  AND  ELEVATION  OF  PIPING. 

taken  proportional  to  the  equivalent  glass  surface,  which  in  every 
case  is  to  be  considered  as  the  actual  glass  surface  plus  ±  the 
exposed  wall  surface.  From  this  surface  about  I  heat-unit  will  be 
transmitted  from  each  square  foot  for  each  degree  difference 
of  temperature  between  that  inside  and  outside  per  hour;  that 
is,  if  the  difference  of  temperature  is  70  degrees,  each  square 


240 


HEATING   AND    VENTILATING   BUILDINGS. 


foot  of  glass  surface  would  transmit  70  heat-units  per  hour. 
The  radiating  surface  usually  employed  for  this  purpose  is 
horizontal  pipe,  and  hence  is  of  the  most  efficient  kind.  From 
a  surface  of  this  nature  we  can  consider  without  sensible  error 
that  2.2  heat-units  are  given  off  from  each  square  foot  for  each 

A 


FIG.  194.-  PIPING  FOR  OUTSIDE  BENCH. 


FIG.  195. — PIPING  FOR  INSIDE  BENCH. 

degree  difference  of  temperature  between  the  radiator  and  the 
air  of  the  room  per  hour.  From  this  data  a  table  can  be 
computed  which  gives  the  ratio  of  equivalent  glass  surface 
to  radiating  surface,  in  which  the  results  will  be  found  to 
agree  well  with  average  practice ;  the  results  are  to  be  in- 
creased or  diminished  10  to  20  per  cent,  according  as  the  cir- 


DESIG-N  OF  STEAM  AND   HOT-WATER   SYSTEMS.     24! 


cumstances  of  exposure  or  the   quality  of  the  building  vary 
more  or  less  from  the  average  condition. 

TABLE  SHOWING  AMOUNT  OF  GLASS  SURFACE  OR  ITS  EQUIVA- 
LENT WHICH  MAY  BE  HEATED  BY  i  SQUARE  FOOT  OF 
RADIATING  SURFACE  IN  GOOD  BUILDINGS. 


Hot  Water. 

Steam. 

Temp,  of  Radiating  Surface,  Deg.  F. 

160° 

1  80° 

200      5  Ibs.  227° 

10  Ibs.  240° 

Square  Feet  of  Glass  for  i  Square  Foot  of 
Radiating  Surface 

Temp,  of  surrounding  air,  90°  F.  .. 

1.9 

2-3 

2.8 

3-3 

3-S 

80°  F.  .  . 

2-3 

2.9 

3-5 

4.0 

46 

"       '              "                  70°  F.  .  . 

3-o 

3-6 

4-2 

5-o 

5-7 

**       *             "                  60°  F. 

4.0 

4.6 

5.25 

6.0 

7.0 

4  '       *              *  *                   ^  o'J  F 

5-0 

6.0 

6.8 

8.0 

9.0 

.,"      '             "             *    40°  F... 

6.9 

8.0 

8.2 

IO.O 

ii.  5 

From  the  data  above  the  following  table  is  computed, 
which  gives  the  radiation  in  square  feet  required  for  green- 
louses  or  conservatories  with  different  amounts  of  glass  sur- 
:aces.  It  also  gives  divisors  from  which  the  heating-surfaces 
or  grate-surfaces  in  the  boilers  may  be  computed  by  dividing 
the  given  amount  of  radiation.  Thus  for  a  greenhouse  with 
1000  feet  of  glass  surface,  which  is  to  be  kept  at  70  degrees  in 
the  coldest  weather,  we  note  in  the  table  that  200  square  feet 
of  radiation  will  be  required  ;  the  heating-surface  in  the  boiler 
will  be  200  divided  by  5.6  (=  36)  square  feet,  and  the  area  of 
grate  will  be  (200  divided  by  156  =)  1.28  square  feet. 
GREENHOUSE  HEATING  WITH  STEAM. 


Square  feet  of  glass    .    
Radiation  required,  sq.  ft.,  tempt.  40. 

!  •  . 

1  9 

250 
25 

500 
50 

75° 
75 

IOOO 
IOO 

1500 
J5o 

2OOO 
200 

2500 
250 

3000 
300 

4000  j  5000 

400  500 

10.000 

1,000 

"      "     "   50- 

I  ; 

33 

62 

82 

125 

188 

250 

3'3 

375 

500 

625 

1,250 

"       "      '*     "   60. 

tc 

43 

84 

I25 

167 

250 

333 

416 

500 

660 

830 

1,  660 

"       "       *'     "   70. 

ad 

50 

100 

ISO 

200 

300 

400 

500 

600 

800 

IOOO 

2,000 

•  **       "      "     "   80. 

•S 

64 

125 

1  88 

25° 

35° 

500 

625 

75° 

IOOO 

1250 

2,500 

Divisor  of  Radiation. 
ror  heating  surface  in  boiler  

4 

4-5 

5-i 

5-4 

5.6 

6.0 

6.2 

6-5 

6.7 

6.9 

7.0 

7 

•"or  area  of  grate    ,  25  1^2 

138 

144 

156 

160 

1  80 

190 

192 

204 

216 

240 

GREENHOUSE  HEATING  WITH   HOT  WATER. 


Square  feet  of  glass 

Water  160°. 
Radiation  sq.  ft.  tempt.  40 

\\  5° — 

60 

-        '••     '•'•    E"..-.: 

Divisors  of  Radiation. 

ror  heating  surface 

ror  grate  surface  '.  . 


15 

25  62 
83 
37 

6.5  6.8 
1901  193 


no!  145 
i ro  200 

187!  250 
250  333 
333 


:-i- 


r.- 


7.6  8.i«  8.4  9.0  9.3  10.0  10.4  10.5 
207  216  232  252  270  288  306  324 


2500  3000  4000 


r 

625 

833  looo 

1330 


--• 


330 


[660 

l66o  2100 


3-333 


IO.5   12. 0 

[42    360 


242  HEATING  AND    VENTILATING  BUILDINGS. 

The  sizes  of  main  pipes  should  be  the  same  as  those  which 
are  used  for  direct  heating,  page  237. 

Relative  Tests  of  Hot-water  and  Steam  Heating  Plants. — 
Several  tests  have  been  made  to  determine  the  relative 
efficiency  and  economy  of  steam  and  hot-water  heating  plants. 
The  first  test  so  recorded  was  made  at  the  Massachusetts 
Agricultural  College  by  Professor  S.  T.  Maynard,  the  results 
of  which  are  given  in  Bulletins  4,  6,  and  8,  issued  by  the  Mass. 
Exp.  Station,  1889  and  1890.  In  this  test  two  houses  were  used 
which  were  located  as  nearly  as  possible  with  equal  exposure, 
and  the  tests  were  made  with  great  care  and  by  entirely  disin- 
terested observers.  The  following  is  a  summary  of  the  results 
and  conclusions  as  taken  from  the  bulletins  : 

STEAM-HEAT    VERSUS   HOT   WATER. 
[From  Bulletin  No.   4.] 

In  order  to  get  at  some  facts  in  regard  to  this  subject,  so  important  to 
the  grower  of  plants  under  glass,  and  gain  some  positive  knowledge  as 
to  the  relative  value  of  the  two  systems,  two  houses  were  constructed 
during  the  summer  of  1888,  75  X  18  feet,  as  nearly  alike  as  possible  in  every 
particular.  Two  boilers  of  the  same  pattern  and  make  were  put  in,  one 
fitted  for  steam  and  one  for  hot  water;  the  steam  for  heating  the  east 
house,  and  the  hot  water  for  the  west  and  most  exposed  one.  The  boilers 
were  completed  and  ready  for  work  in  November  and  were  used  until 
January  9,  1889,  when  these  experiments  began. 

Records  of  temperature  of  each  house  were  made  at  7.30  and  9  A.M., 
and  3,  6,  and  9  P.M.  Sufficient  coal  was  weighed  out  each  morning  for  the 
day's  consumption  and  the  balance  not  consumed  deducted  the  next  morn- 
ing. "  The  two  boilers  and  fittings  were  put  in  so  as  to  cost  the  same 
sum  and  were  warranted  to  heat  the  rooms  satisfactorily  in  the  coldest 
weather." 

These  experiments  were  repeated  during  the  months  of  January  and 
February,  1889,  and  in  summarizing  the  results  it  was  found  that  the  steam- 
boiler  consumed  during  the  two  months  referred  to  6582  Ibs.  of  coal, 
while  the  hot-water  boiler  consumed  in  the  same  time  only  5174  Ibs.,  a 
saving  in  favor  of  the  latter  of  nearly  20  per  cent.  At  the  same  time  the 
temperature  of  the  room  heated  by  hot  water  averaged  1.7°  higher  than 
that  heated  by  steam. 

The  temperature  was  more  even  where  heated  by  hot  water,  and  con- 
sequently there  was  less  danger  from  sudden  cold  weather.  This  was 
strikingly  shown  on  the  night  of  February  22. 

The  average  outside  temperature  for  the  day  was  34°. 

At  9  P.M.  it  was  above  32°,  and  proper  precautions  not  having  been  taken 
for  so  sudden  a  change  as  followed  (the  average  temperature  during  the    j 
23d  of  February  was  2°),  at  6  o'clock   on   the  morning  of  the  23d  the  tem- 


DESIGN  OF  STEAM  AND   HOT-WATER   SYSTEMS.     243 


perature  of  the  room  heated  by  steam  was  29°,  while  in  that  heated  by  hot 
water  it  was  35°.   .  .   . 

[From  Bulletin  No.  6.] 

The  boilers  used  were  built  of  cast-iron  sections.  In  the  hot-water 
boiler  five  sections  are  used,  the  area  of  heating  surface  exposed  to  the 
fire  being  74.5  feet. 

The  steam-boiler  consists  of  eight  sections,  the  total  heating  surface  of 
which  is  85.12  feet. 

The  experiments  reported  in  the  April  Bulletin  were  continued  during 
the  two  following  months  of  March  and  April,  and  from  the  tables  show- 
ing the  comparative  results  the  following  summary  is  appended: 
SUMMARY  FOR  HOT-WATER  BOILER. 

Total  coal  consumed  by  hot-water  boiler  from  December  23,  1888,  to 
[April  24,  1889,  4  tons  1155  Ibs.  Average  daily  temperature  for  the  four 

months,  53.5°. 

SUMMARY  FOR  STEAM-BOILER. 

Total  coal  consumed  by  steam-boiler  from  December  23,  1888,  to  April 
\,  1889,  5  tons  1261  Ibs.     Average  daily  temperature  for  the  four  months, 
,1.2°. 

It  will  be  seen  by  the  above  that  the  average  temperature  of  the  house 
icated  by  hot  water  was  2.3°  higher  than  that  heated  by  steam,  and  that 
ic  amount  of  coal  consumed  was  2106  Ibs.  less  in  the  former  than  in  the 
itter. 

[From  Bulletin  No.  8,  April,  1890.] 

Much  discussion  having  been  provoked  relative  to  the  accuracy  of  the 
isults  of  experiments  with  steam  and  hot  water  for  heating  greenhouses, 
sported  in  Bulletins  No.  4  and  6,  we  have  the  past  winter  made  a  care- 
ful repetition  of  the  experiments  to  correct  any  errors  that  might  be  found 
md  to  verify  previous  results. 

The  boilers  having  been  run  with    the  greatest    care  possible   from 
)ecember  i,  1889,  to  the  present  date,  March  18,  1890,  and  every  precaution 
laving  been  taken  that  no  error  should  occur,  we  give  the   results  in 
the  following  table: 


HOT  WATER. 

STEAM. 

Lettuce  and  Carnation  Room. 

Lettuce  and  Carnation  Room. 

Month. 

ill 

d 

ill 

sll 

sl 

*f! 

V 

u   6   3 

O  4)  £j 

11 

*j  fcWC  4> 

3  n  a 

"2'S  a 

•o-q  S 

"2  rt"o. 

Jl* 

•O--;  « 

c  0  o. 

"2'S  c. 

•n  be  4) 

C   rt   Q. 

<n  " 

Ofcg 

—  -jg  g 

1-1  .5  E 

*"•  t  S 

""•5  S 

*"  «  S 

•^_3 

r 

H 

H 

<~ 

t- 

H 

December  .  . 

34.99" 

41-52° 

57° 

47-59D 

1505 

40.21° 

51.69° 

46.39° 

2350 

January  .... 

33.27 

44-35 

62.48 

51-41 

2304 

42.72 

61          49-45 

3202 

February.  .  . 

32.04 

43-67 

65.96 

52-54 

1704 

42.42  !66-32 

51.01 

2540 

March, 

17  days 

29-75 

39-94 

58-83 

47-44 

1085 

39.16 

58.11 

46.73 

1692 

Averages.  .  . 

32-5ic 

42-37° 

61.06° 

49-74° 

Total 
6593 

41.12° 

59-28° 

43.39° 

Total 
9784 

UNIVERSITY 


244 


HEATING   AND    VENTILATING   BUILDINGS. 


SUMMARY  FOR  HOT-WATER  BOILER. 

Total  coal  consumed  from   December  i,  1889,  to  March   18,  1890,  659$ 
Ibs.     Average  daily  temperature  for  the  time,  49.74°. 

SUMMARY  FOR  STEAM-BOILER. 

Total  coal  consumed   from  December  i,  1889,  to  March   18,  1890,  9784 
Ibs.     Average  daily  temperature  for  the  time,  48.39°. 

A  saving  of  fuel  in  favor  of  hot  water  of  about  33  per  cent. 

Similar  tests  were  made  under  the  general  direction  of  Prof, 
L.  R.  Taft  at  the  Michigan  Experiment  Station  and  are  to  be 
found  reported  in  full  in  a  paper  by  the  writer,  read  before  the 
American  Society  of  Mechanical  Engineers,  Volume  XI.  For 
this  test  two  houses  were  used,  each  of  the  same  size  and  of  the 
same  grade  of  construction.  The  houses  were  equally  exposed 
to  the  heat  of  the  sun,  but  the  hot-water  house  was  rather  more 
exposed  to  the  wind.  The  general  method  of  testing  was 
essentially  the  same  as  that  described,  and  the  results  show 
substantially  the  same  difference.  The  heaters  used  were  cast- 
iron  of  the  drop-tube  form,  quite  different  from  those  used  in 
Massachusetts,  but  well  adapted  for  the  work. 

The  following  table  gives  a  summary  of  the  results : 

SUMMARY  OF  RESULTS  OF  TEST   OF  HOT  WATER  AND  STEAM. 


Year. 

1889 

1890 

Months. 

December. 

10 

January. 

February. 

March. 

April. 

Days  of  Experiment. 

3* 

28 

20 

3° 

Steam. 

£ 

X 

8 

re 

<U 

c/5 

£ 
EC 

1 

V 

c7$ 

£ 

£ 

1 
C/J 

£ 

33 

1 
c/5 

£ 
ffi 

Total  coal  

1025 
93-2 

31-8 
38.5 
35-1 
53-9 
54-9 

825 

75 

31.8 
38.5 
35-1 
54-9 

60.3 
13 

3475 

112.  I 

27.7 
38 
27.2 

52.5 

53-8 
4.4 

2799 
90.3 

27-7 
38 
27.2 
54-i 

54.8 
4 

3400 
121.4 

22 

33-8 
27 
54-1 

53-5 
4-3 

2775 
99.1 

22 
33-8 
27 
54-4 

56 

4.2 

2714 
II4.4 

19.2 
29.2 

22.  0 

53-3 

55-7 

2288 
135-7 

19.2 

29.2 

22.0 

54-3 

57 

1800 
60 

36.2 
42 
38 
51.8 

54-9 
5-9 

1800 
60 

36.2 
42 

38 

58.4 

60.2 
4-3 

Average  coal  per  day.  . 
Average  outside  temper- 
ature, 6  A.M  
Average  outside  temper- 
ature, 4  P.M  
Average  outside  temper- 
ature   9PM 

Average    inside   temper- 
ature   6AM  

Average    inside    temper- 
ature 9  P.M  

DESIGN   OF  STEAM  AND   HOT-WATER   SYSTEMS.     245. 

During  the  month  of  April,  1890,  the  same  amount  of  coal 
was  burned  in  both  heaters  in  order  to  see  what  the  effect 
would  be  on  the  resulting  temperature  of  the  two  houses.  The 
results  gave  a  temperature  which  averaged  8.5  degrees  higher 
in  the  hot-water  house  than  in  the  steam-heated  house. 

Experiments  were  made  by  Prof.  L.  H.  Bailey,  of  Cornell 
University,  in  1891  with  houses  which  were  not  similar  either 
as  to  exposure  or  methods  of  piping,  the  results  of  which  were 
in  general  somewhat  more  favorable  to  steam  than  to  hot 
water.  In  1892  Prof.  Bailey  arranged  the  same  room  so  that  it 
could  be  alternately  heated  with  steam  and  hot  water.  The 
results  of  this  last  test  so  far  as  economy  is  concerned  were  also 
somewhat  in  favor  of  the  steam-heat.  The  general  conclusions 
which  Prof.  Bailey  drew  from  this  test  were  as  follows : 

CONCLUSIONS. 

Under  the  present  conditions  the  following  results  can  be  deduced. 
It  will  be  observed  that  they  confirm  several  of  the  conclusions  of  last 
year. 

1.  Hot  water  maintained  a  slightly  greater  average  difference  between 
the  minimum  inside  and  outside  night  temperature  than  steam. 

2.  There  was  practically  no  difference  in  the  coal  consumption  under 
the  two  systems. 

3.  With  a  small  plant  like  this  the  fluctuations  under  both  systems 
are  much  greater  than  in  larger  ones,  and  neither  proved  very  satis- 
factory. 

4.  The  utility  of  slight  pressure  in  enabling  steam  to  overcome  un- 
favorable conditions  is  fully  demonstrated. 

5.  The  addition  of  crooks  and  angles  is  decidedly  disadvantageous  to 
the  circulation  of  hot  water  and  of  steam  without  pressure,  but  the  effect 
is  scarcely  perceptible  with  steam  under  low  pressure. 

6.  In  starting  a  new  fire  with  cold  water,  circulation  commences  with 
hot  water  sooner  than  with  steam,  but  it  requires  a  much  longer  time 
for  the  water  to  reach  a  point  where  the  temperature  of  the  house  will 
be  materially  affected. 

/.  The  length  of  pipe  to  be  traversed  is  a  much  more  important  con- 
sideration with  water  than  with  steam. 

8.  A  satisfactory  fall  towards  the  boiler  is  of  much  greater  importance 
with  steam  than  the  manner  of  placing  the  pipes. 

129.  Heating  of  Workshops  and  Factories. — Work- 
shops or  factories  where  counter-shafts  and  belting  are  running 
which  keeps  the  air  in  agitation  can  be  heated  satisfactorily  by 


246  HEATING   AND    VENTILATING    BUILDINGS. 

erecting  coils  of  pipe  for  radiating  surface  near  the  ceiling  of 
the  room.  Coils  made  with  branch-tees,  as  described  in  Article 
64,  page  107,  may  be  used,  with  the  pipes  placed  in  a  hori- 
zontal plane  and  parallel  to  each  other.  In  such  a  position  the 
radiating  surface  is  very  efficient,  and  the  heat  given  off  as  shown 
by  experiment  is  a  maximum.  In  a  coil  located  near  the  ceil- 
ing the  temperature  of  the  room  in  the  upper  portion  will  be 
come  very  high  and  will  not  be  evenly  distributed  unless  the 
air  is  mechanically  agitated,  so  that  the  overhead  system  of 
piping  is  only  satisfactory  in  shops  and  places  where  there  are 
moving  belts  or  other  means  for  agitating  the  air.  The  method 
of  proportioning  supply-pipes  and  radiating  surface  for  this 
case  has  already  been  considered.  Mr.  C.  J.  H.  Woodbury 
gives,  in  Vol.  VI,  page  861,  "  Transactions  of  American  Society 
Mechanical  Engineers,"  considerable  useful  data  relating  to 
this  method  of  heating.  It  is  the  favorite  method  for  heating 
cotton-mills,  about  one  foot  in  length  of  i|--inch  pipe  being 
used  for  90  cubic  feet  of  space. 

NOTE.— In  the  preceding  discussion  a  loss  of  50  per  cent  due  to  fric- 
tion has  been  assumed  as  probable  in  flues  and  registers  through  which 
air  discharges  into  a  room.  This  is  a  reasonable  allowance  under  many 
conditions,  but  on  the  other  hand  is  fully  double  the  loss  which  will  be 
experienced  in  flues  which  are  smooth  and  well  aligned,  and  provided 
with  long  and  easy  turns.  When  the  conditions  are  favorable,  flues 
which  have  an  area  of  two  thirds  those  specified  in  the  table  on  page  233 
will  be  perfectly  satisfactory. 


CHAPTER  XL 

HEATING    WITH    EXHAUST   STEAM.     NON-GRAVITY 
RETURN-SYSTEMS. 

130.  General  Remarks. — Steam  after  being  employed  in 
engine  contains  the  greater  portion  of  its  heat,  and  if  not 

:ondensed  or  utilized  for  other  purposes  it  can  usually  be  em- 
>loyed  for  heating  without  materially  affecting  the  power 
>f  the  engine.  The  systems  of  steam-heating  which  have  been 
lescribed  are  those  in  which  the  water  of  condensation  flows 
lirectly  into  the  boiler  by  gravity.  In  other  systems  in  use 
ugh-pressure  steam  is  carried  in  the  boilers,  high-  or  low- 
>ressure  steam  in  the  heating-mains  and  radiators,  and  the 
;turn-water  of  condensation  is  received  by  a  trap  and  de- 
livered either  into  a  tank  from  which  it  is  pumped  into  the 
boiler  or  in  some  instances  wasted.  The  exhaust  steam 
lay  need  to  be  supplemented  by  live  steam  taken  directly 
rom  the  boiler,  which  may  be  reduced  in  pressure  either  by 
issing,  through  a  valve  partly  open,  or  a  reducing-valve,  as 
described  in  Article  137. 

It  will  often  be  found  that  little  attempt  is  made  to  utilize 
:the  heat  escaping  in  the  exhaust  steam  from  non-condensing 
engines,  and  consequently  a  good  opportunity  exists  for  con- 
struction of  systems  which  will  save  annually  many  times 
their  first  cost. 

131.  Systems  of  Exhaust  Heating.— The  exhaust  steam 
discharged  from  non-condensing  engines   contains  from  20  to 
30  per  cent  of  water,  and  considerable  oil  or  greasy  matter 
which  has  been  employed  in  lubricating.     When  the  engine  is 
freely  exhausting  into  the  air,  the  pressure  in  the  exhaust-pipe 
is,  or  should  be,  but  slightly  in  excess  of  that  due  to  the  atmos- 

247 


248  HEATING   AND    VENTILATING   BUILDINGS. 

ph£re.  The  effect  of  passing  exhaust  steam  through  heating- 
pipes  is  likely  to  increase  the  resistance  and  cause  back  press- 
ure which  will  reduce  the  effective  work  of  the  engine.  The 
engine  delivers  steam  discontinuously,  but  at  regular  intervals 
at  the  end  of  each  stroke.  The  amount  is  likely  to  vary  with 
the  work  done  by  the  engine,  since  the  engine-governor  is 
always  adjusted  to  admit  steam  in  such  amount  as  is  required^ 
to  preserve  uniform  speed;  if  the  work  is  light  very  little  steam 
will  be  admitted  to  the  engine.  For  this  reason  the  supply 
available  for  heating  varies  within  wide  limits. 

The  general  requirements  for  a  successful  system  of  exhaust- 
steam  heating  must  be,  first,  the  arrangement  of  a  system  of 
piping  having  such  proportions  as  will  make  little  or  no- 
increase  in  back  pressure  on  the  engine  and  will  provide  for^ 
using  an  intermittent  supply  of  steam  ;  second,  provision  for 
removing  the  oil  from  the  exhaust,  since  this  will  interfere 
materially  with  the  heating  capacity  of  the  radiating  surfaces  ; 
third,  provision  against  accidents  by  use  of  a  safety  or  back- 
pressure valve  so  arranged  as  to  prevent  damage  to  the  engine 
by  sudden  increase  in  back  pressure. 

These  requirements  can  be  met  in  various  ways.     To  pren 
vent  sudden  change  in  back  pressure  due  to  irregular  supply  of 
steam   the    exhaust-pipe    from   the  engine  should  be  carried : 
directly  to  a  closed  tank  whose  cubic  contents  should   be  at 
least  30  times  that  of  the  engine  and  as  much  larger  as  practi- 
cable.    This  tank  can  be  provided  with  diaphragms  or  baffle- 
plates  arranged  so  as  to  throw  all  or  nearly  all  the  grease  and 
oil  in  the  steam  into  a  drip-pipe,  from  which  it  is  removed  by] 
means  of  a  steam-trap,  as   described   in  Article  98,  page   164,] 
To  this  tank  may  be  connected  a  relief-pipe  leading  to  the  back- 
pressure valve,  and  also  a  supplementary  pipe  for  supplying 
live  steam.     The  supply  of  steam  for  heating  should  be  drawn 
from  the  top  of  the  tank. 

Any  system  of  piping  may  be  adopted,  but  extreme  care 
should  be  taken  that  as  little  resistance  as  possible  is  introduced  j 
at  bends  or  fittings.     The  radiating  surface  employed  should] 
be  such  as  will  give  the  freest  possible  circulation.     In  general, 
that  system  will  be  preferable  in  which  the  main  steam-pipe  is] 
carried   directly  to  the  top  of  the  building,  the   distributing- 


HEATING    WITH  EXHAUST  STEAM. 


249 


pipes  run  from  that  point,  and  the  radiating  surface  is  supplied 
by  the  down-flowing  current  of  steam  (Fig.  173).  It  is  desir- 
able to  have  a  closed  tank  at  the  highest  point  of  the  system, 
from  which  the  distributing-pipes  are  taken,  and  provided  with 
drips  leading  to  a  trap  so  as  to  remove,  before  it  can  reach 
the  radiating  surface,  any  water  of  condensation  or  oil  which 
has  been  carried  to  the  top  of  the  building. 

132.  Proportions  of  Radiating  Surface  and  Main  Pipes 
Required  in  Exhaust  Heating. — The  size  of   exhaust  pipe 
required  for  an   engine  of  given  power,  in  order  that  the  back 
^pressure  shall  not  exceed  a  certain  amount,  may  be  computed, 
She  only  data  required  in  addition  to  that  already  given  for 
heating  with  live  steam,  being  that  relating  to  the  steam  re- 
Quired  by  engines.     The    amount  of  steam  used  by  engines 
will  depend   upon  the  workmanship  and  class  to  which  they 
belong,    but  we  can    assume  with    little   error   that    non-con- 
densing engines  will  require  the  following  weights  of  steam  per 
horse-power    per    hour :    simple   with    throttling-governor   40 
pounds,  with  automatic  governor  35  pounds,  with  Corliss  valves 
30  pounds  ;  compound  using  high-pressure  steam  25   pounds. 
In  order  that  the  pipes  may  be  sufficiently  large  it  is  better  to 
proportion  the  systems  for  the  more   uneconomical  type. 

TABLE  OF  DATA  FOR  COMPUTATION. 


Absolute  

M-7 

16.7 

18.7 

24.7 

12.7 

97 

216 

Temperature  of  air  

70 

70 

70 

70 

70 

Heat   per  min.   from   100    sq.  ft.   radia'ion  in 

' 

B.  T.  U.  equal  3  times  difference  

426 

438 

447 

4<>6 

5°7 

402 

366 

966 

067 

067 

067 

062 

Latent  heat  steam  B   T  U     

966 

963 

* 
960 

946 

978 

-.6   ! 

16.2 

Cubic  feet  steam  to  weigh  %  Ib  .     ... 

17.6 

16.4 

14.0 

10.8 

20.2 

26.0 

Cubic  feet  steam  required  each  min.  to  supply 

ii  6 

8  8 

12.6 

Weight  of  T  cubic  foot  steam  Ibs. 

0.0379 

.O4O3 

.0640 

.0326 

("Throttling 
Radiating  surface  per  H.  P  •{  Qortiss*  ' 

152 
114 

146 
129 
no 

143 
127 
107 

139 

122 

104 

126 

112 

95 

162 
I46 
122 

179 
158 

[Compound 

95 

91 

9° 

87 

79 

IO2 

112 

Head  of  steam  in  feet  equal  i  foot  water  of 

water  column  . 

1669 

1585 

U55 

1317 

IOIO 

1902 

2440 

In  the  following  discussion  the  dimensions  of  piping 
are  computed  for  an  engine  using  40  pounds  of  steam  per 
horse-power  per  hour  (f  pound  per  minute),  and  exhausting 


250  HEATING  AND    VENTILATING   BUILDINGS. 

against  a  back  pressure  above  or  below  atmosphere  as  stated.* 
The  preceding  table  gives  properties  of  steam,  also  radiating 
surface  supplied  per  horse-power  by  engines  of  various  classes. 

The  computation  of  the  size  of  exhaust-pipes  can  be  made  by  the 
following  algebraic  process  : 

Let  V  equal  velocity  of  the  steam  in  feet  per  second  ;  v,  velocity  in 
feet  per  minute;  /,  length  of  pipe  in  feet;  D,  diameter  of  pipe  in  feet; 
d,  diameter  in  inches;  A,  area  of  pipe  in  square  feet;  Q,  cubic  feet  of 
steam  discharged  per  minute  ;  h,  back  pressure  above  atmosphere  ex- 
pressed in  feet  of  steam  ;  p,  back  pressure  expressed  in  pounds  per  square 
inch  ;  HP,  horse-power  of  engine  ;  c,  number  of  cubic  feet  in  one  pound  I 
of  steam. 

From  the  formulae,  page  218,  we  have,  for  velocity  in  feet  per  second 

7/>;,   .  .  .  .   d 


from  which  by  reduction  the  velocity  in  feet  per  minute 


The  discharge  in  cubic  feet  per  minute 

Q  =  Av  =  3000.4  V^-D  =  4723  \  -jd\   .    .    .     .     (3) 

Since  f  pound  of  steam  is  used  per  horse-power  per  minute, 

Q=  IcHP.     ......     .......     (4) 

From  above  by  reduction 

^  =  0.537^  =  o.457l/f^r;      '.    ....     (5) 

HP  =  7.'35V/!5f    •     '    •     •    '     .......     (6) 

In  case  the  back  pressure  is  equal  to  one  foot  of  water  column 
(0.433  pound  per  square  inch)  above  atmosphere,  h  =  1598,  <:  =  25.7, 
and  we  have 


For  one  pound  back  pressure 

HP=  i.i 

It  is  advisable   to  make  the  diameter  one  inch  greater  to 
overcome  additional  resistances.     (See  table.) 

*  Radiating  surface  25  per  cent  less.     See  Article  121,  page  218. 


HEATING    WITH  EXHAUST  STEAM. 


251 


RADIATING    SURFACE    AND    HORSE-POWER  OF    ENGINE  FOR  A 
GIVEN  DIAMETER  OF  EXHAUST-PIPE. 


Diam.  Exhaust- 
steam  Pipe  ioo 
Ft.  Long.  Back 
Pressure  not 
to  Exceed 
0.4  Lb. 

Correspond- 
ing H.  P.  of 
Engine. 

Radiating   Sur- 
face in  Sq.  Ft. 
Supplied  by 
AutotnaticType 
of  Engine. 

Diam.  Kxhaust- 
steam  Pipe  ioo 
Ft.  Long.  Back 
Pressure  not 
to  Exceed 
0.4  Lb. 

Correspond- 
ing H.  P.  of 

Engine. 

Radiating  Su;- 
face  in  Sq.  Ft. 
Supplied  by 
AutomaticType 
of  Engine. 

Inches. 

Inches. 

2 

1.  12 

no 

6 

63 

6,2OO 

a| 

3-J 

300 

7 

99-3 

9.500 

3 

6.4 

605 

9 

304 

19,500 

3i 

n.  i 

1.050 

12 

356 

34,000 

4 

17-5 

1,650 

14 

562 

54,000 

4* 

22-9                       2,2OO 

16 

825 

89.000 

5 

36.6 

3.400 

18 

M5o 

110,000 

The  foregoing  table  is  computed  for  steam  having  a  pressure 
of  0.43  pound  above  the  atmosphere.  For  other  pressures  of 
exhaust  multiply  the  results  given  in  the  table  by  the  following 
factors  (for  other  distances  multiply  by  0.1  ^ l)\ 


Pressure. 

Factor. 

Atmospheric  
2  pounds  below  .  . 
5  pounds  below.  . 
2  pounds  above..  . 
3  pounds  above..  . 
10  pounds  above.  . 

1.05 
1.125 
1.27 
0.98 
0.895 
0.79 

As  an  example ;  find,  the  size  of  exhaust-pipe  and  amount 
••of  radiating  surface  supplied  by  the  exhaust  of  a  50  horse- 
I  power  engine  of  the  automatic  type,  working  against  a  back 
*•'••  pressure  of  0.43  pound.     For  this  condition,  the  exhaust  from 
one  horse-power  will  supply  25  per  cent  less  than  131  square  feet 
of  radiation  (see  table  page  249),  or  4900  square  feet.     From 
the  table  at  top  of  page  we  see  that  a  6-inch  pipe  will  be  some- 
what larger  than  required,  but  should  be  used.     The  amount  of 
|   radiating  surface  needed  to  warm  a  given  building  will  depend 
I  on  pressure  of  the  steam,  exposure,  and  class  of  building,  as 
explained  on  page  55. 

133.  Systems  of  Exhaust-heating  with  Less  than  At 
mospheric  Pressure. — If    a  system  of   exhaust-heating   dis- 
charge the  water  of  condensation  directly  into  the  atmosphere, 
the  pressure  must  be  slightly  above  atmospheric ;   but  systems 


252 


HEATING   AND    VENTILATING   BUILDINGS. 


DISCHARGE j 

FIG.  196. — SIPHON  CONDENSER. 


have  been  used  with  success  in  which  the  back-pressure 
was  less  than  atmospheric,  and  in  the  table  of  proportions 
which  has  been  given  such  cases  are  considered. 

Such  a  system  can   be  constructed  by  connecting  the  dis- 

charge   from   the    system 
to  an  air-pump  which  will 
remove  the  water  of  con- 
densation and  to  a  great 
extent    the    atmospheric 
pressure  ;  the  heating  sur- 
face   will   act    as    a    con- 
denser for  the  engine,  and    j 
in   case   it    is    insufficient 
for  this  purpose  a  jet  or  1 
surface  -  condenser,     sup-    ' 
plied  with  cold  water  may    j 
be  used  to  supplement  it.    ' 
Instead  of  an  air-pump  and    j 
condenser,  a  siphon  con-  ,j 
denser,   Fig.  196,  may  be 
used.     This  latter  instru- 
ment  is  regularly  on  the  || 
market,  and  consists  of  a 
chamber  above  a  conver- 
gent tube  which  receives  jj| 
the  exhaust  steam  and  a  ! 
jet   of  water.     This    con-  | 
denser    depends    for     its 
action  upon  the  fact  that 
a  column  of  water  34  feet  in  height  will  balance  and  overcome 
the  atmospheric  pressure.     For  its  successful  use  it  must  be 
set  so  that  the  top  of  the  condenser  is  at  least  34  feet  higher 
than  the  end  of  the  discharge-tube,  the  bottom  of  which  is  to 
be  submerged. 

In  a  .system  of  exhaust  heating  by-pass  connections  to  the  j 
condenser  should  be  provided,  so  that  the  heating  surface  would 
not  need  to  be  used  in  warm  weather. 

Besides   the   general   system  which   has   been    described, 
other  systems  of  great  merit  have  been  devised  and  put  on 


HEATING    WITH  EXHAUST  STEAM, 


253 


the  market  with  many  special  and  patented  features.  Of  these 
we  may  mention  first  the  Willames  system,  which  is  shown  in 
Fig.  197,  with  details  of  construction.  It  will  be  seen  that  the 
exhaust  from  the  engine  is  received  into  a  large  upright 
stand-pipe  with  back-pressure  valve  at  top,  and  that  the  steam 
is  drawn  from  near  the  top,  and  after  passing  through  the 


radiating  system,  is  received  into  a  large  branch-tee,  which  is 
supplied  with  injection-water  and  serves  as  a  condenser.  The 
suction-pipe  of  the  air-pump  is  connected  to  the  branch-tee 
and  acts  to  remove  the  atmospheric  pressure  from  the  entire 
system.  A  by-pass  for  summer  use  is  shown.  Water  is  heated 


254 


HEATING   AND    VENTILATING   BUILDINGS. 


in  the  closed  hot-water  tank  by  a  portion  of  the  return,  and 
may  be  used  for  any  purpose  needed,  as,  for  instance,  feed- 
water  for  boilers,  heating  by  hot-water  circulation,  etc. 

Another  system  of  this  kind  which,  by  increasing  the  effi- 
ciency of  surface,  has  met  with  much  favor  is  that  invented 
by  Andrew  G.  Paul.  This  differs  in  construction  and  principle 
of  operation  from  that  described,  in  that  instead  of  using  an  air-^ 
pump  which  receives  all  the  exhaust,  a  small  tank  is  connected 
with  an  induction  condenser  called  an  exhauster,  which  is  con- 
nected to  all  the  drips  and  to  the  air-valves  of  the  radiators.  An 
automatic  device  stops  the  operation  of  the  exhauster  as  soon 
as  the  air  is  removed.  The  advantages  of  this  system  depend 
principally  upon  the  quick  removal  of  air  from  the  various 
radiators  and  pipes,  which  constitutes  the  principal  obstruction 
to  circulation  ;  the  inductive  action  in  many  cases  is  sufficient  to 
cause  the  system  to  operate  at  a  pressure  slightly  below  the  .' 
atmosphere.  Fig.  198  is  a  diagram  *  showing  an  application 


FIG.  198. — PAUL  SYSTEM. 

of  the  Paul  system  to  the  exhaust-piping  of  a  steam-engine. 
The  connections  of  two  radiators  are  shown,  one  of  which  is  of 
the  single-pipe,  the  other  of  the  two-pipe,  system.  The  ex- 
hauster, shown  in  the  lower  left-hand  corner,  receives  all  the 

*  Heating  and  Ventilation,  November  15,  1894. 


'HEATING    WITH  EXHAUST  STEAM. 


255 


drips  from  the  piping  and  radiators,  and  is  connected  with  the 
air-valve  of  each  radiator. 

134.  Combined  High-  and  Low-pressure    Heating-sys- 
tems.— In  nearly  all  systems  of  heating  with  exhaust  steam  it  is 


necessary  to  arrange  the  piping  so  that  at  times  live  steam  may 
be  admitted  in  any  amount  required,  as  substantially  described 
in  Article  130. 

In  some  instances  high-pressure  steam  is  carried  in  the 
boiler  and  may  possibly  be  used  in  a  few  radiators,  while  the 
principal  part  of  the  building  is  heated  with  low-pressure  steam 


HEATING   AND    VENTILATING   BUILDINGS. 


which  is  drawn  directly  from  the  boiler,  and  is  reduced  in  press- 
ure by  passing  through  a  reducing-valve.  In  this  case  the 
return-water  of  condensation  passes  to  a  tank  or  chamber  at  the 
lowest  portion  of  the  system,  and  is  fed  into  the  boiler  by  means 
of  a  return-trap  or  steam-pump.  The  principal  elements  of  such 
a  system  is  shown  in  Fig.  199,  as  designed  by  the  Albany  Steam 
Trap  Company,  and  forms  a  useful  illustration  of  the  method 
of  piping  essential.  To  start  the  pump  automatically  and  to 
keep  it  moving  at  the  proper  speed  a  pump-governor  (Article 
135)  is  used. 

135.  Pump-governors. — In  non-gravity  systems  of  heating 
the  water  of  condensation  is  returned  to  the  boiler  by  return- 
traps,  as  described  in  Article  99,  page  167,  or  by  steam-pumps. 
The  trap  is  automatic,  and  when  in  good  order  will  operate 
without  attention,  but  the  ordinary  steam-pump  needs  to  be 
started  and  stopped,  as  required,  to  remove  the  water.  To 
render  the  pump  automatic  a  device  termed  a  pump-governor 
is  often  employed.  Many  forms  are  used,  but  they  con- 
sist in  nearly  every  case  of  a  tank  containing  a  float  or  equiv- 
alent device,  connecting  with  levers  to  the  valve  which  admits 

steam  for  operating  the  pump. 
The  tank  is  connected  to 
the  suction  and  located  above 
the  pump.  When  the  tank  is 
full  of  water,  the  steam-pump 
is  put  in  operation  by  the 
rising  of  the  float,  which  opens 
the  steam-valve.  When  the 
tank  is  empty,  the  float  falls, 
closing  the  steam-valve  and 
thus  stopping  the  pump. 

A  pump  governor  consist- 
ing of  a  float-trap  with  outside  connections  to  a  steam-valve,  as 
described  by  F.  Barren,*  is  shown  in  Fig.  200. 

A  steam-pump  with  attached  governor  is  shown  partly  in 
section  Fig.  201.  In  this  case  the  float  is  of  the  bucket  form, 
the  valve  for  supplying  steam  to  the  pump  is  flat  with  a  single 


FIG.  200  — PUMP-GOVERNOR  WITH 
OUTSIDE  LEVERS. 


*  Pleating  and  Ventilation,  March,  1894. 


HEATING    WITH  EXHAUST  STEAM.  2$? 

port,  and  is  connected  by  an  internal  lever  to  the  bucket  in 
such  a  manner  that  when  the  tank  is  filled  the  valve  will  be 
opened  and  the  pump  will  operate,  and  when  the  tank  is 
empty  the  valve  will  be  closed,  and  the  pump  will  stop. 

The  pump-governors  are  frequently  set  some  little  distance 


FIG.  2OT. — INTERNAL  CONNECTED  PUMP-GOVF.RNOR. 

from  the  pump,  but  attached  in  every  case  so  as  to  produce 
the  results  described. 

136.  The  Steam-loop. — A  device  which  has  been  used 
quite  extensively  for  returning  water  of  condensation  to  the 
boiler  when  the  pressure  has  been  reduced  only  a  few 
pounds  is  called  a  steam-loop,  the  construction  and  principle 
of  operation  of  which,  as  described  by  Walter  C.  Kerr,  is  as 
follows : 

The  figure  shows  the  loop  returning  the  water,  from  a 
separator  attached  to  an  engine-main,  to  a  boiler  above  the 
separator  level.  "  From  the  separator  drain  leads  the  pipe 
called  the  '  riser,'  which  at  a  suitable  height  empties  into  the 
horizontal.  This  runs  back  to  the  drop-leg,  connecting  to  the 
boiler  anywhere  under  the  water-line.  The  riser,  horizontal, 
and  drop-leg  form  the  loop,  and  usually  consist  of  pipes  varying 
in  size  from  three  quarters  of  an  inch  to  two  inches,  and  are 
wholly  free  from  valves,  the  loop  being  simply  an  open  pipe, 


HEATING   AND    VENTILATING   BUILDINGS. 


giving  free  communication  from  separator  to  boiler.  (Stop- 
and  check-valves  are  inserted  for  convenience,  but  take  no 
part  in  the  loop's  action.)  "  Supposing,  for  example,  the  boiler- 
pressure  to  be  100  pounds  and  the  pressure  at  the  separator 
reduced  to  95.  "  The  pressure  of  95  pounds  at  the  separator 
extends  (with  even  further  reduction)  back  through  the  loop, 


f 


Jff 


FIG.  202.— THE  STEAM-LOOP. 

but  in  the  drop-leg  meets  a  column  of  water  (indicated  by  the 
broken  line)  which  has  risen  from  the  boiler,  where  the  pressure 
is  100  pounds,  to  a  height  of  about  19  feet,  that  is,  to  the  hydro- 
static head  equivalent  to  the  5  pounds  difference  in  pressure. 
Thus  the  system  is  placed  in  equilibrium.  Now  the  steam  in 
the  horizontal  condenses,  lowering  slightly  the  pressure  to  94 
pounds,  and  the  column  in  the  drop-leg  rises  two  feet  to 
balance  it ;  but  meanwhile  the  riser  contains  a  column  of  mixed 
vapor,  spray,  and  water,  which  also  tends  to  rise  to  supply  the 
horizontal,  as  its  steam  condenses,  and  being  lighter  than  the 
solid  water  of  the  drop-leg  it  rises  much  faster.  By  this  proc- 
ess the  riser  will  empty  its  contents  into  the  horizontal,  whence 
there  is  a  free  run  to  the  drop-leg  and  thence  to  the  boiler." 

137.  Reducing-valves. — The  reducing-valve  is  a  throttling- 
valve  arranged  to  be  operated  automatically  so  as  to  reduce 
the  pressure  and  also  to  maintain  a  constant  pressure  on  the 
steam-mains.  A  great  many  forms  of  these  valves  are  in 
common  use.  In  one  a  diaphragm  of  metal  or  rubber  is  em- 
ployed, as  in  Fig.  203.  The  low-pressure  steam  acts  on  one 
side  of  the  diaphragm,  a  weight  or  spring  which  may  be  set  at 
any  desired  pressure  on  the  other  side.  This  diaphragm  is 


HEATING    WITH  EXHAUST  STEAM.  26 1 

The  three  important  requisites  in  the  construction  of  such 
plants  are,  first,  a  removal  of  all  surface-water  so  that  it  cannot 
possibly  come  in  contact  with  the  steam-pipe  ;  second,  provision 
for  taking  up  expansion  of  pipe  and  keeping  it  in  proper 
alignment ;  and,  third,  insulation  of  the  pipe  from  heat  losses. 

The  first  condition,  which  is  the  most  important  of  all,  is 
also  the  most  likely  to  be  overlooked,  and  many  failures  to 
secure  economic  transmission  have  been  caused  by  allowing 
the  surface-water  to  come  in  contact  with  the  heated  pipes. 
This  water  can  be  removed  by  the  construction  of  a  drain 
beneath  or  by  the  side  of  the  pipe-system,  provided  with 
proper  outlets.  A  perfect  drainage-system  for  the  soil  is  in 
every  case  an  essential  requisite  for  success. 

Provision  for  expansion  may  be  made  by  the  use  of  expan- 
sion-joints, as  already  described  in  Article  62,  page  105,  or  by 
the  use  of  elbows  and  right-angled  offsets  arranged  to  partly 
turn  as  the  line  expands.  The  writer  has  had  experience 
with  various  forms  of  these  joints,  and  found  nothing  equal  to 
the  straight  expansion-joint,  Fig.  90,  which  should,  however,  be 
constructed  so  that  it  cannot  by  any  possible  accident  be  pulled 
apart ;  this  may  be  done  either  by  use  of  an  internal  lug  or 
external  brace.  These  joints  should  be  thoroughly  anchored, 
so  that  they  will  stay  in  position,  and  should  be  placed  suf- 
ficiently close  together  to  take  up  all  expansion  without  strain 
on  the  pipe-line.  If  the  ordinary  slip-joints  are  used,  they 
will  need  to  be  placed  at  distances  of  about  120  feet  apart. 
The  pipe  between  the  joints  should  rest  on  rollers  or  connect- 
ing hangers  which  permit  its  free  motion.  If  elbows  and  off- 
sets are  employed  to  take  up  expansion,  there  will  be  an 
abrupt  change  in  grade,  and  if  any  part  dips  below  the  main 
steam-line  it  should  be  drained  by  a  pipe  connecting  to  a  trap 
or  to  the  return.  If  bends  convex  upward  are  necessary,  means 
must  be  provided  for  removing  the  air. 

In  general,  in  systems  where  the  steam  is  transmited  long 
distances  the  best  results  will  be  possible  only  when  the  boiler- 
plant  can  be  located  on  lower  ground  than  the  buildings  to 
be  heated,  so  that  the  water  of  condensation  may  be  returned 
by  gravity.  This  cannot  always  be  done,  and  in  many  cases 
it  will  only  be  possible  to  return  the  water  of  condensation  by 


HEATING   AND    VENTILATING   BUILDINGS. 


giving  free  communication  from  separator  to  boiler.  (Stop- 
and  check-valves  are  inserted  for  convenience,  but  take  no 
part  in  the  loop's  action.)  "  Supposing,  for  example,  the  boiler- 
pressure  to  be  100  pounds  and  the  pressure  at  the  separator 
reduced  to  95.  "  The  pressure  of  95  pounds  at  the  separator 
extends  (with  even  further  reduction)  back  through  the  loop, 


FIG.  202. — THE  STEAM-LOOP. 

but  in  the  drop-leg  meets  a  column  of  water  (indicated  by  the 
broken  line)  which  has  risen  from  the  boiler,  where  the  pressure 
is  100  pounds,  to  a  height  of  about  19  feet,  that  is,  to  the  hydro- 
static head  equivalent  to  the  5  pounds  difference  in  pressure. 
Thus  the  system  is  placed  in  equilibrium.  Now  the  steam  in 
the  horizontal  condenses,  lowering  slightly  the  pressure  to 
pounds,  and  the  column  in  the  drop-leg  rises  two  feet  to 
balance  it ;  but  meanwhile  the  riser  contains  a  column  of  mixed 
vapor,  spray,  and  water,  which  also  tends  to  rise  to  supply  the 
horizontal,  as  its  steam  condenses,  and  being  lighter  than  the 
solid  water  of  the  drop-leg  it  rises  much  faster.  By  this  proc- 
ess the  riser  will  empty  its  contents  into  the  horizontal,  whence 
there  is  a  free  run  to  the  drop-leg  and  thence  to  the  boiler." 

137.  Reducing-valves. — The  reducing-valve  is  a  throttling- 
valve  arranged  to  be  operated  automatically  so  as  to  reduce 
the  pressure  and  also  to  maintain  a  constant  pressure  on  the 
steam-mains.  A  great  many  forms  of  these  valves  are  in 
common  use.  In  one  a  diaphragm  of  metal  or  rubber  is  em- 
ployed, as  in  Fig.  203.  The  low-pressure  steam  acts  on  one 
side  of  the  diaphragm,  a  weight  or  spring  which  may  be  set  at 
any  desired  pressure  on  the  other  side.  This  diaphragm  is 


.  HE A  TING    WITH  EXHAUST  STEAM.  26 1 

The  three  important  requisites  in  the  construction  of  such 
plants  are,  first,  a  removal  of  all  surface-water  so  that  it  cannot 
possibly  come  in  contact  with  the  steam-pipe  ;  second,  provision 
for  taking  up  expansion  of  pipe  and  keeping  it  in  proper 
alignment ;  and,  third,  insulation  of  the  pipe  from  heat  losses. 

The  first  condition,  which  is  the  most  important  of  all,  is 
also  the  most  likely  to  be  overlooked,  and  many  failures  to 
secure  economic  transmission  have  been  caused  by  allowing 
the  surface-water  to  come  in  contact  with  the  heated  pipes. 
This  water  can  be  removed  by  the  construction  of  a  drain 
beneath  or  by  the  side  of  the  pipe-system,  provided  with 
proper  outlets.  A  perfect  drainage-system  for  the  soil  is  in 
every  case  an  essential  requisite  for  success. 

Provision  for  expansion  may  be  made  by  the  use  of  expan- 
sion-joints, as  already  described  in  Article  62,  page  105,  or  by 
the  use  of  elbows  and  right-angled  offsets  arranged  to  partly 
turn  as  the  line  expands.  The  writer  has  had  experience 
with  various  forms  of  these  joints,  and  found  nothing  equal  to 
the  straight  expansion-joint,  Fig.  90,  which  should,  however,  be 
constructed  so  that  it  cannot  by  any  possible  accident  be  pulled 
apart  ;  this  may  be  done  either  by  use  of  an  internal  lug  or 
external  brace.  These  joints  should  be  thoroughly  anchored, 
so  that  they  will  stay  in  position,  and  should  be  placed  suf- 
ficiently close  together  to  take  up  all  expansion  without  strain 
on  the  pipe-line.  If  the  ordinary  slip-joints  are  used,  they 
will  need  to  be  placed  at  distances  of  about  120  feet  apart. 
The  pipe  between  the  joints  should  rest  on  rollers  or  connect- 
ing hangers  which  permit  its  free  motion.  If  elbows  and  off- 
sets are  employed  to  take  up  expansion,  there  will  be  an 
abrupt  change  in  grade,  and  if  any  part  dips  below  the  main 
steam-line  it  should  be  drained  by  a  pipe  connecting  to  a  trap 
or  to  the  return.  If  bends  convex  upward  are  necessary,  means 
must  be  provided  for  removing  the  air. 

In  general,  in  systems  where  the  steam  is  transmited  long 
distances  the  best  results  will  be  possible  only  when  the  boiler- 
plant  can  be  located  on  lower  ground  than  the  buildings  to 
be  heated,  so  that  the  water  of  condensation  may  be  returned 
by  gravity.  This  cannot  always  be  done,  and  in  many  cases 
it  will  only  be  possible  to  return  the  water  of  condensation  by 


262  HEATING   AND    VENTILATING   BUILDINGS. 

a  pump  located  in  one  of  the  buildings  to  be  heated,  and 
regulated  by  a  pump-governor.  This  in  some  cases  may  in- 
volve more  expense  than  will  be  warranted  by  the  saving  due 
to  returning  the  water  of  condensation. 

For  the  insulation  of  the  pipe  many  methods  have  been 
adopted,  of  which  we  may  mention  first  the  wooden  tube 
and  concentric  air-space  surrounding  the  pipe,  Fig.  205.  The 


FIG.  205. — PIPE  WITH  WOODEN-TUBE  INSULATION. 

tube  is  usually  made  by  sawing  out  the  interior  portion  of  a 
log,  leaving  a  shell  or  wall  about  two  inches  thick.  Each 
length  is  provided  with  a  mortise  and  tenon  joint,  and  the  dif- 
ferent lengths  are  joined  together  by  driving.  These  wooden 
tubes  are  slipped  over  the  steam-pipe  as  it  is  laid,  the  pipe 
being  held  in  a  central  position  by  collars,  so. as  to  leave  an  air- 
space about  one  inch  thick  surrounding  the  pipe.  This  pipe  is 
usually  strongly  banded  with  hoop-iron,  and  the  joints  can 
be  made  water-tight  when  laid,  but  checks  soon  form  in  the 
wood-pipe  and  make  crevices  through  which  the  soil-water  can 
reach  the  steam-pipe.  Recently  a  form  of  tube  made  of  two 
layers  of  inch  board  separated  by  tarred  felting  has  come  into 
use  and  is  in  general  to  be  preferred  to  the  solid  tube  as  hav- 
ing superior  insulating  qualities.  A  view  of  such  tubing  partly 
in  section  is  shown  in  Fig.  206. 


FIG.  206. — WYCKOFF  BUILT-UP  WOOD  TUBING. 

The   wooden-tube   system    of    insulation   is   objectionable, 
.principally  because  it  does  not  protect  the  pipe  from  ground- 


HEATING    WITH  EXHAUST  STEAM,  263 

water,  its  durability,  as  proved  by  experience,  is  not  great,  and 
leaks  in  the  steam-pipe  are  very  difficult  to  locate  and  repair. 
[A  modified  plan  of  the  construction  described  has  been  em- 
[ployed,  in  which  both  steam-  and  return-pipes  were  covered 
••with  asbestos  and  hair-felt  and  placed  in  a  box  made  of  2-inch 
plank ;  the  box  was  laid  on  a  concrete  bottom  three  inches  thick, 
|and  after  the  pipes  were  laid  it  was  completely  surrounded 
Fwith  concrete.  This  was  arranged  so  that  the  steam-pipes 
would  not  be  disturbed  by  decay  of  the  wood.  The  concrete 
would  in  that  event  support  the  steam-pipes  and  constitute  a 
protecting  tube.  The  heat  insulation  proved  on  trial  to  be 
much  superior  to  that  of  the  solid  wooden  tube,  while  its  cost 
was  somewhat  less.  Similar  constructions  in  which  the  wooden 
tube  has  been  replaced  by  sewer-pipe  are  in  use  and  are  of 
superior  durability.  In  one  case  familiar  to  the  writer  a 
wooden  tube  lined  with  sewer-pipe  was  laid  outside  the  steam- 
pipe,  the  whole  being  covered  with  earth  ;  such  a  construction 
replaced  one  shown  in  Fig.  205,  but  in  practice  its  heat-insula- 
:tion  properties  have  not  proved  to  be  better. 

The  best  system  of  transmitting  steam  long  distances,  but 
probably  also  the  most  expensive,  is  to  be  obtained  by  build- 
ing a  conduit  lined  with  brick  or  masonry  laid  in  cement  and 
sufficiently  large  for  inspection  and  repairs.  The  pipe  should 
'be  carried  in  it  on  proper  hangers  and  thoroughly  wrapped  with 
insulating  material,  as  described  in  Article  116,  page  200. 
Every  required  condition  can  be  easily  met  in  this  construc- 
tion. 

The  loss  of  heat  from  systems  protected  by  a  simple  wooden 
tube  is  considerable,  rising  in  many  cases  to  from  30  to  40  per 
cent  of  that  from  the  bare  pipe.  This  is,  however,  due  to  the 
poor  system  of  insulation  used,  since  it  should  not  exceed  in 
any  case  20  per  cent  of  that  from  naked  pipe  (see  page  199). 
The  loss  from  the  underground  system  of  piping  at  Cornell 
University,  which  is  somewhat  over  one  half  mile  in  length,  and 
in  which  the  steam-pipes  are  laid  inside  of  sewer-pipe,  with  a 
wooden  tube  outside  the  sewer  pipe,  the  whole  covered  with 
about  4  feet  of  earth,  causes  the  consumption  of  about  two  and 
one  half  tons  of  coal  per  day,  which  is  about  10  per  cent  of  the 
total  coal  consumption  when  the  plant  is  working  at  normal 


264  HEATING   AND    VENTILATING   BUILDINGS. 

capacity.  This  heat  loss  is  very  nearly  a  constant  amount  and 
cannot  be  expressed  as  a  fixed  percentage  of  the  total  steam 
used,  for  the  reason  that  when  the  steam  consumption  is  large 
this  percentage  of  loss  is  small  and  vice  versa. 

High-pressure  steam  for  power  purposes  is  also  sometimes 
transmitted  in  this  manner  and  engines  operated  at  a  great 
distance  from  the  boiler-plant.  The  losses  from  such  a  system 
of  transmission  are  often  serious,  especially  if  a  long  pipe-line 
has  to  be  kept  hot,  and  if  the  engine  is  operated  only  a  part  of 
the  time  or  only  at  partial  capacity.  Where  the  engine  is 
worked  to  its  full  capacity,  the  loss  is  usually  less  than  by  any 
other  system  of  transmission.  The  following  paragraph  gives 
a  careful  estimate,  based  on  actual  experiment,  of  the  loss  ex- 
perienced in  transmitting  constant  power  by  various  methods 
a  distance  of  1000  feet. 

The  loss  in  transmitting  power  by  any  system  is  principally 
constant,  and  hence  when  the  power  is  greatly  increased  the 
percentage  is  correspondingly  reduced.  The  following  estimate 
is  based  on  the  transmission  of  loo  horse-power  1000  feet : 

Percentage 

Method  of  Transmission.  of  Loss. 

Line  shafting : 

Loss  by  friction (average  32)  25  to  40 

Electricity : 

Loss  in  transforming  from  mechanical  to  electri- 
cal, and  vice  versa 20  to  30 

Line  loss 2  to    5 

Total  loss,  electrical  transmission 22  to  35 

Conveying  steam  : 

Naked  steam-pipe  (still  air) 37  to  45 

Pipe  covered  with  solid  wood  and  earth n  to  13 

For  operating  machinery  which  is  required  occasionally  or  at 
intervals  electricity  is  no  doubt  the  most  economical  medium, 
since  when  the  demand  for  power  ceases  the  expenditure  on 
account  of  transmission  also  becomes  nothing,  which  is  rarely 
the  case  either  with  line-shafting  or  steam. 

The  diagram,  Fig.  207,  gives  the  summary  of  the  results  of 
a  test  of  the  Lehigh  Coal-storage  Plant,  South  Plainfield,  N.  J., 


HEATING    WITH  EXHAUST  STEAM. 


265 


made  by  the  writer  to  determine  the  heat  lost  in  supplying 
an  engine  situated  740  feet  from  a  boiler-house,  the  connecting 


2  4  6  8  10          12          (4          16          18         20         22         24         26         28 

FIG.  207.— DIAGRAM  SHOWING    RESULTS  OF  TEST  TO  DETERMINE    HEAT  LOSSES  IN 

UNDERGROUND  PIPE. 

pipe-line  consisting  of  250  feet  of  6-inch,  106  feet  of  5-inch, 
and  391  feet  of  4-inch  pipe,  having  a  total  radiating  surtace  of 
1057.5  square  feet. 


266  HEATING   AND    VENTILATING   BUILDINGS. 

The  engine  was  1 2-inch  diameter,  i6-inch  stroke,  running 
with  a  piston  speed  of  about  600  feet  a  minute,  thus  producing, 
when  cutting  off  at  one  third  stroke,  a  velocity  of  steam  of 
about  60  feet  per  second  in  the  4-inch  supply-pipe.  As  this 
pipe  was  391  feet  long,  more  reduction  in  pressure  was  antici- 
pated than  was  actually  found.  As  shown  by  the  summary 
which  follows,  the  actual  reduction  varied  from  5  to  7  pounds, 
averaging  6  pounds. 

The  general  method  of  testing  adopted  was  such  as  to  give 
information,  first,  of  the  amount  of  water  in  the  steam  as  it 
entered  the  steam-pipe ;  second,  the  amount  of  water  in  the 
steam  as  it  reached  the  engine  ;  third,  the  amount  of  water 
collected  at  intervening  drips  ;  fourth,  the  total  amount  of  steam 
used  ;  fifth,  the  fall  in  pressure  between  the  boilers  and  engine. 
These  determinations  were  made  as  follows :  The  amount  of 
water  in  the  steam  was  determined  by  a  throttling  calorimeter, 
the  sample  of  steam  being  drawn  in  each  case  from  a  vertical 
pipe  located  close  to  a  bend  from  a  horizontal,  and  collected 
by  a  half-inch  nipple  extending  past  the  centre  of  the  vertical 
pipe.  The  drip  was  caught  at  places  which  had  been  provided 
in  the  pipe,  and  was  weighed  from  time  to  time. 

The  barometer  readings  were  taken  with  an  aneroid  which 
had  been  compared  with  a  mercurial  barometer.  The  cor- 
rected readings  are  given  in  the  summary  as  well  as  in  the  dia- 
gram. Simultaneous  observations  of  the  quantities  given  in 
the  summary  were  taken  every  ten  minutes.  A  study  of  the 
summary  shows  that  the  loss  was  sensibly  constant  during  the 
run.  This  is  clearly  shown  by  noting  the  fact  that  any  increase 
in  the  amount  of  steam  flowing  through  the  line  had  the  effect 
of  decreasing  the  percentage  of  moisture  at  the  engine. 

The  total  heat  loss  per  hour  was  equivalent  to  that  required  to 
evaporate  (36  -f-  45.1  =)  81.1  pounds  of  water  from  a  tempera- 
ture of  314°  F.,  to  a  pressure  of  70.1  pounds  by  gauge.  This 
is  equal  to  (81.1  X  893  —  )  72,322  B.  T.  U.  The  average 
steam-pressure  was  70.1  pounds  by  gauge,  its  temperature 
313.6°  F.,  the  average  outside  temperature  16.6°  F.;  hence 
the  difference  of  temperature  was  297°.  The  loss  for  each  de- 
gree difference  of  temperature  between  that  of  outside  air  and 
that  of  steam  becomes  (78,342  -^  297  =  )  243.7  B.  T.  U.  per 


-HEATING    WITH  EXHAUST   STEAM.  26? 

hour.  The  total  radiation  surface  was  1057.5  square  feet; 
hence  the  loss  in  B.  T.  U.  per  square  foot  per  hour  was  0.229 
per  degree  difference  of  temperature. 

This  for  a  difference  of  temperature  of  150°  corresponds  to 
0.17  B.  T.  U.  per  degree  difference  per  square  foot  per  hour, 
an  amount  about  10  per  cent  of  that  which  would  have  been 
given  off  from  a  naked  pipe.  (See  page  66.) 

The  loss  by  condensation  varied  from  3  to  8  per  cent,  the 
loss  of  pressure  and  consequent  ability  to  do  work  about  6  per 
cent.  The  total  loss  was  not  far  from  10  per  cent  from  both 
these  causes ;  if  this  had  been  proportional  to  length,  it  would 
have  been  13.5  per  cent  for  a  line  1000  feet  in  length. 

The  diagram  shows  variations  in  the  observed  quantities  as 
they  occurred  from  time  to  time.  It  is  to  be  noted  that  as 
the  demand  for  steam  at  the  engine  was  large  the  moisture  in 
the  steam  delivered  was  correspondingly  reduced. 


CHAPTER   XII. 
HEATING   WITH  JOT 

139.  General  Principles. — The  general  laws  which  apply 
to  hot-air  heating  have  already  been  considered  in  the  articles 
relating  to  Ventilation  and  to  the  Methods  of  Indirect  Heat- 
ing with  Steam  or  Hot  Water.*     The  method  of  heating  with 
hot  air,  as  usually  practised,  consists  in  first  enclosing  a  suit- 
able heater,  termed  a  furnace,  in  a  small  chamber  with  brickj 
or  metallic  walls,  which  is  connected  to  the  external  air  by  a 
flue  leading  to  its  lower  portion  and  to  the  various  rooms  to 
be  heated  by  smaller  flues  leading  from  the  upper  part.     In 
^operation  the  cold  air  is  drawn  from  the  outside,  is  warmed  by 
)coming  in  contact  with  the  heated  surfaces  of  the  furnace,  and 
/is  discharged  through  the  proper  flues  or  pipes  to  the  various 
f  rooms.     The  rapidity  of  circulation  depends  entirely  upon  the 
/   temperature  to  which  the  air  is  heated  and  the  height  of  the 
flue  through  which  it  passes  ;  the  velocity  will  be  in  every  case 
essentially  as  given  in  the  table  on  page  45.     In  order  that  a 
system  of    circulation   may  be   complete    flues    must   be  pro- 
vided for  the  escape  of  the   cooler  air  from  the  room  to  be 
heated,  otherwise    the^rirru^gtu^witt  be  very  uncertain  and 
the  heating  quite  unsatisfactory.      Registers  and  flues  for  the 
escape  of  the  air  from  the  room  are  often  neglected,  although 
fully  equal  in  importance  to  those  leading  to  the  furnace. 

Regarding  the  relative  merits  of  hot-air  heating  by  furnace 
as  described  and  of  the  various  systems  of  steam  or  hot-water 
heating,  little  can  be  said  in  a  general  way,  since  so  much  de- 
pends on  circumstances  and  local  conditions.  It  is  rarely  that 
these  systems  come  in  direct  competition.  The  force  which 

*  See  pages  52  and  211. 

268 


HEATING   WITH  HO 7'  AIR.  269 

causes  the  circulation  of  the  heated  air  is  a  comparatively 
feeble  one  and  may  be  entirely  overcome  by  a  heavy  wind ; 
consequently  it  is  generally  found  that  the  horizontal  distance 
to  which  heated  air  will  travel  under  all  conditions  is  short ; 
hence  the  system  is  in  general  not  well  adapted  for  large 
buildings.  When  properly  erected  and  well  proportioned,  this 
system  gives,  in  buildings  of  moderate  size,  very  satisfactory 
results. 

It  may  be  said,  however,  that,  in  erecting  a  hot-air  system 
of  heating,  competition  has  been  in  many  cases  so  sharp  as 
to  induce  cheap,*rather  than  good,  construction.  Small  fur- 
naces have  been  used  in  which  the  temperature  of  the  ex- 
terior shell  had  to  be  kept  so  high,  in  order  to -meet  the 
demands  for  heat,  that  the  heated  air  absorbed  noxious  gases 
from  the  furnace  and  entered  the  room  in  such  condition  as  to 
impair,  rather  than  to  improve,  the  ventilation.  Ventilation- 
ducts  for  removing  the  air  from  the  rpoms  have  often  been 
neglected,  and  hence  the  results  obtained  have  been  far  from 
satisfactory.  Such  faults  are  to  be  considered,  however,  as 
those  of  design  and  construction  rather  than  as  pertaining  to 
;the  system  itself. 

In  order  that  the  hot-air  system  should  be  satisfactory  in 
even-  respect,  the  furnace  should  be  sufficiently  lajtge,  and  the 
ratio  of  heating  surface  to  grate  such  that  a  large  quantity  of 
air  may  be  heated  a  comparatively  small  amount  rather  than 
that  a  small  quantity  shall  be  heated  a  great  amount.  As 
air  takes  up  heat  very  much  more  slowly  than  steam  or  water, 
it  would  seem  that  the  relative  ratio  of  heating  surface  to 
grate  surface  should  be  more  than  that  commonly  employed 
in  steam-heating.  By  studying  the  proportions  which  have 
already  been  given  for  steam-heating  boilers  (page  125)  it  will 
be  seen  that  the  ratio  of  heating  surface  to  grate  surface  for 
the  steam-boiler  varies  between  20  and  45,  averaging  about  32. 
From  a  study  of  the  results  in  catalogues  of  manufacturers  df 
furnaces  the  ratio  of  air-heating  surface  to  grate  surface  in  hot- 
air  furnaces  seems  to  vary  from  20  to  50  as  extremes.  These 
proportions  are  essentially  the  same  as  used  in  steam-heating 
and  are  much  too  small  for  the  best  results  in  hot-air  heating. 
It  is  quite  evident  that  since  air  cannot  be  heated  by  radiation, 


27O  HEATING   AND    VENTILATING   BUILDINGS. 

and  is  warmed  only  by  the  contact  of  its  particles  against  the 
heated  surface,  that  the  exterior  form  of  the  furnace  should  be 
such  as  will  induce  a  current  of  air  to  impinge  in  some  por- 
tion of  its  course  directly  against  the  surface. 

Regarding  the  economy  of  this  or  any  other  system  of  indirect 
heating,  it  is  simply  a  question  of  perfect  combustion  and  rela- 
tive wastes  of  heat.  If  the  fuel  is  perfectly  burned  and  all  the 
heat  which  is  given  off  is  usefully  applied,  the  system  is  per- 
fect. The  waste  of  heat  in  any  system  of  combustion  is  that 
due  to  loss  in  the  ashes,  to  radiation,  and  to  escape  of  hot 
gases  into  the  chimney.  If  the  furnace  is  properly  encased 
and  if  the  hot-air  pipes  are  well  covered,  there  is  no  reason 
why  losses  from  imperfect  combustion  and  from  radiation 
should  not  be  a  minimum.  The  chimney  loss  depends  largely 
upon  the  temperature  of  the  surface  of  the  heater :  if  this  is 
high,  the  loss  will  be  large.  In  general,  it  may  be  said  that 
the  larger  the  heating  surface  provided  the  lower  may  be 
its  temperature,  and  the  greater  the  economy.  It  should  be 
noted,  however,  that  this  or  any  system  of  indirect  heatingi 
requires  the  consumption  of  more  fuel  than  when  the  heating 
surfaces  are  placed  directly  in  the  room,  and  for  that  reason! 
the  operating  expense  must  be  considerably  greater  than  that 
of  direct  systems  of  hot-water  and  steam  heating.  (See  page 
202.) 

Furnaces,  or  in  fact  heating-boilers  of  any  kind,  are  un- 
economical if  operated  with  a  deficient  supply  of  air.  In  this; 
case  the  product  of  combustion  will  contain  carbon  monoxide,*' 
an  extremely  poisonous  and  inflammable  gas,  which  is  quite 
likely  to  take  fire  and  burn,  on  coming  in  contact  with  air,  at 
the  base  or  top  of  the  chimney. 

140.  General  Form  of  a  Furnace. — The  principles  which 
apply  in  furnace  construction  are  not  essentially  different  from 
those  already  given  in  Chapter  VII  for  steam  and  hot-water 
boilers.  In  the  case  of  a  hot-air  furnace  the  fire  and  heated 
products  of  combustion  are  on  one  side  of  the  shell  and  the 
air  to  be  warmed  on  the  other.  In^the  case  of  steam  or  hot- 
water  boilers  the  water  and  steam  occupy  the  same  relative! 


*  See  Article  24,  page  26. 


HEATING    WITH  HOT  AIR.  2JI 

>sitions  as  the  air  in  the  case  of  the  hot-air  furnaces.  The 
rpes  and  forms  of  furnaces  which  are  in  use  may  be  classified 
ictly  the  same  as  heating-boilers,  Articles  77  and  82,  as 
having  plain  or  extended  surface,  and  as  being  horizontal  or 
vertical,  tubular  or  sectional;  it  may  be  said  that  the  forms 
which  are  in  use  are  fully  as  numerous  as  those  described  for 
steam-heating -and  hot-water  heating. 

The  material  which  is  employed  in  construction  is  usually 
cast  iron  or  steel,  and  there  is  a  very  g*eat  difference  of  opinion 
as  to  the  relative  merits  of  the  two.  It  seems  quite  probable 
that  cast  iron,  because  of  its  rough  surface,  may  be  a  better 
medium  for  giving  off  heat  than  wrought  iron  or  steel,  but  it 
is  quite  certain  that  at  a  very  high  temperature,  some  carbon 
from  the  cast  iron  will  unite  with  the  oxygen  from  the  air 
forming  carbonic  acid.  When  very  hot  it  may  be  slightly 
permeable  to  the  furnace  gases.  Such  objections  are,  how- 
ever, of  little  practical  importance,  since  the  temperature  of  a 
furnace  never  should,  and  never  does  if  properly  proportioned, 
exceed  300  or  400  degrees  Fahr.,  and  for  this  condition  the 
difference  in  heating  power  of  cast  iron  and  steel  is  very 
slight.  It  is  of  great  importance  that  the  shell  of  the  furnace 
be  tightj  so  that  smoke  and  the  products  of  combustion  can- 
not enter  the  air-passages. 

Furnaces  can  be  purchased  with  or  without  magazine  feed, 
but  the  demand  of  late  years  is  principally  for  those  without 
the  magazine,  since  it  has  not  been  proved  to  present  any 
special  advantages. 

Furnaces  are  often  set  in  a  chamber  surrounded  with  brick 
walls,  as  explained  for  steam-boilers,  but  they  are  more  fre- 
quently set  inside  a  metallic  casing,  this  latter  being  termed  a 
portable  setting  ;  this  casing  varies  somewhat  as  constructed  by 
different  makers,  but  usually  consists  of  two  sheets  of  metal,  the 
outer  of  galvanized  iron,  with  intervening  air-space  empty  or 
filled  with  asbestos.  The  casing  is  placed  at  such  a  distance  from 
the  furnace  as  to  provide  ample  room  for  the  passage  of  air. 

Some  form  of  dumping  or  shaking  grate  which  can  be 
readily  and  quickly  cleaned  is  almost  invariably  employed. 
The  draft-doors  which  admit  air  below  the  grate  and  check- 
dampers  in  the  stovepipe  are  usually  arranged  so  they  can  be 


2/2  HEATING   AND    VENTILATING   BUILDINGS. 

opened  or  closed  from  some  convenient  place  on  the  first  floo 
of  the  house  by  means  of  chains  passing  over  guide-pulleys. 

A  pan  in  which  water  may  be  kept  is  added  to  every  fur- 
nace   for  the  purpose  of  increasing  the  moisture  in  the   air 
this    is   of   importance,    since   the    heated    air   requires    mor 
moisture  than  cold  to  maintain  a  comfortable  degree  of  satur 
tion,as  explained  in  Article  28,  page  30. 

141.  Proportions  Required  for  Furnace  Heating.— The 
proportion  of  the  area  of  heating  surface  in  the  furnace  to  that 
of  the  grate  cannot  be  computed  from  any  data  accessible  to 
the  writer,  and  the  proportions  given  are  assumed  to  be  twice 
those  which  have  been  found  to  give  best  results  in  steam-heat- 
ing ;  these  apparently  agree  well  with  the  best  practice.  The 
tables  which  are  given  are  computed  for  a  maximum  tempera- 
ture of  120°  F.  for  the  air  leaving  the  furnace,  which  is  50 
degrees  in  excess  of  the  ordinary  temperature  in  the  house. 
No  doubt  better  practice  might  require  the  introduction  of 
more  air  at  a  lower  temperature,  but  considering  the  fact  that 
this  high  temperature  only  has  to  be  maintained  when  the 
outside  weather  is  extremely  cold,  it  seems  quite  doubtful  if 
the  expense  of  a  furnace  large  enough  for  this  additional  duty, 
would  be  warranted. 

The  ratio  which  the  grate  surface  of  the  furnace  should  bear 
to  the  glass  and  exposed  wall  surface  of  the  room  can  be  com- 
puted with  sufficient  accuracy  from  known  data  relating  to  the 
heat  contained  in  coal  and  to  the  probable  efficiency  of  com- 
bustion. The  heat  given  off  from  the  walls  of  a  room  for  each 
degree  difference  of  temperature  between  the  inside  and  out- 
side has  been  shown  on  page  59  to  be  approximately  equal 
to  the  area  of  the  glass  plus  one  quarter  the  area  of  the  exposed 
wall  surface,  which  we  will  in  this  place  denominate  as  the 
equivalent  glass  surface.  One  pound  of  good  anthracite  coal 
will  give  off  about  13,000  heat-units  in  combustion.  One 
pound  of  soft  or  bituminous  coal  will  give  off  in  combustion 
from  10,000  to  15,000  heat-units,  depending  on  the  kind  and 
quality.  Of  this  amount  a  good  furnace  should  utilize  70  per 
cent.*  The  amount  of  coal  which  is  burned  per  square  foot 

*  It  is  quite  probable  that  the  efficiency  of  combustion  in  an  ordinary  fur- 
nace is  much  less  than  the  above,  often  as  low  as  50  per  cent. 


HEATING   WITH  HOT  AIR.  2/3 

of  grate  surface  per  hour  will  depend  very  much  upon  the 
character  of  attendance  ;  in  ordinary  furnaces  used  in  house 
heating,  and  where  it  is  expected  to  replenish  the  fires  only 
two  or  three  times  per  day,  this  amount  is  low,  being  not 
greatly  in  excess  of  3  pounds.  If  the  air  is  120  degrees  in 
temperature,  nearly  60  cubic  feet  will  be  required,  when  heated 
one  degree,  to  absorb  one  heat-unit  (see  Table  VIII),  and  if 
such  air  is  delivered  50  degrees  above  that  of  the  air  in  the 
room,  each  cubic  foot  will  bring  in  f  of  one  heat-unit. 

The  velocity  of  air  in  feet  per  minute  with  ample  allow- 
ance for  friction  is  given  in  a  table  on  page  45,  from  which  it  is 
seen  that  it  will  be  safe  to  assume  velocities  of  4,  5,  and  6  feet 
respectively,  per  second  in  the  flues  or  stacks  leading  to  the 
various  floors.  The  velocity  of  the  air  passing  the  register 
may  be  assumed  as  3  feet  per  second  in  every  case ;  this 
lower  velocity  is  obtained  by  making  the  area  of  the  register 
somewhat  larger  than  that  of  the  pipe  leading  to  it. 

The  following  mathematical  discussion  gives  these  various  consid- 
erations in  general  and  algebraic  terms,  as  follows  : 

Let  F  =  square  feet  in  grate,  C  =  weight  of  coal  burned  per  square 
foot  of  grate  per  hour,  r  =  heat-units  per  pound  of  coal,  E  =  efficiency 
of  furnace,  h  =  heat-units  per  hour,  T  =  temperature  of  air  leaving  fur- 
nace, /'  =  temperature  outside  air,  /  =  temperature  of  room,  G  =  area 
of  glass  in  room,  W  =  area  of  exposed  wall  surface,  H  =  heat  lost  by 
room  for  one  degree  difference  of  temperature,  K=  cubic  feet  of  air 
heated  by  furnace  per  hour,  K'  =  cubic  feet  air  required  to  warm  room. 

We  have,  as  explained, 

//  =  CFEr  =  total  heat  given  off  by  furnace,  equal  to  that  re- 
quired for  all  the  rooms.  .     ...     .     .     .     .     .     .     (i) 

A'  = —  =  cubic  feet  of  air  heated  per  hour  by  furnace.     .     .     (2) 

J.       —    / 

h'  =  (G  +  i  W)(t  —  /')  =  total  he4lt-units  to  warm  the  room.      .     .     (3) 
K  '  =  -       — — —  —  =  cubic  feet  of  air  to  warm  the  room.      ,     (4) 

For  average  conditions  substitute  in  above,  as  explained,  T=  120, 
/  —  70,  /'  =  o,  C  =  .70,  r  =  13,000,  Cr  =  9100,  and  we  have 

h  =  9\ovCF=iK.    .    .     .    .    .    .    .    .    .    .     .     (5) 

K  =  4$$oCF  =  0.56.  .     . (6) 

K'  =  *4(G  +  i  If) (7) 

When  AT  =  AT'.     CF  =  G  +  *W ;  when  C  =  3,  F=  £  +  *?.  (8) 

54.2  162.6 

iJT) (9) 


2/4  HEATING   AND    VENTILATING   BUILDINGS. 

For  computing  areas  of  leader-pipes  and  stacks,  for  resi- 
dence heating,  assume  velocities  which  can  safely  be  taken  as 
follows  :  First  floor,  4  feet  per  second  or  240  per  minute  ; 
second  floor,  5  feet  per  second  or  300  per  minute  ;  third  floor, 
6  feet  per  second  or  360  per  minute.  (See  table,  page  45.) 

Through  a  cross-section  of  the  flue  equal  to  one  square 
inch  100  cubic  feet  will  pass  in  one  hour  when  the  velocity  is 
4  feet  per  second,  125  when  the  velocity  is  5  feet  per  second, 
150  when  the  velocity  is  6  feet  per  second,  25?'  when  the 
velocity  in  feet  per  second  is  represented  by  v. 

Denote  area  of  flue  in  square  inches  by  L\  then  from  equa- 
tion (7) 


2$V  257'  v. 

From  this,  by  transposition,  we  have 


If  for  first-floor  rooms  v  =  4. 


If  for  second-floor  rooms  v  —  5. 


If  for  third-floor  rooms  v  =  6. 


(Also  see  table  on  page  53.) 

The  following  table  gives  the  relative  values  of  these  vari- 
ous quantities,  computed  for  the  conditions  as  explained  : 


HEATING    WITH  HOT  AIR. 


275 


PROPORTIONS    REQUIRED    IN    FURNACE   HEATING. 


Equivalent  glass  surface*  ..  . 
("u.  ft.  air  to  be  heated  per  hr. 
<  irate  area,  square  inches  .  . 
Equivalent    diameter    round 
grate,  inches  
Heating  surface,  square  feet. 
Diameter  smoke-pipe,  inches 
Approximate      cubic     feet  / 
space                                        ) 
Area  stack  — 
ist  floor  (vel.  4)  sq.  in. 
2d      "      (vel.  5)     " 
3d      "     (vel.  6)     " 
Diameter  leader-pipe  —  t 
ist  floor. 
2d     "     .. 
3d     "     -- 
Net  area  register,  sq.  in.  — 
ist  floor  (vel.  3)..  . 
2d      "     and  above 
Area  ventilating  flue  

25 

2100 
22 

7-5 
ii 

50 
4200 

43 
8-5 

21 

75 

f 

9-5 
32 

IOO 

8400 
85 

II.5 
42 

I25 
10,500 
107 

12.5 

53 

150 

12,600 
127 

£5 

200 
I6.800 
170 

'i 

336 
4200 

168 
i35 

112 

J4-7 
13-2 

12 
224 

168 
168 
*35 

250 
21.000 

: 

106. 
7 
4200 
5250 

2IO 

170 
I40 

I6.5 
I4.7 
13-4 

280 
2IO 
210 
I70 

500 
42,000 
425 

24 
212 

8 
8400 

2100 
420 

345 
280 

19 

21 
»9 

S60 
420 
420 

345 

750 
63.000 
640 

29 
320 

10 

12.600 
T5,75<> 

630 
500 

420 

23.2 
25.2 
23.2 

840 
630 
630 
500 

1000 

84,000 

850 

a 

II 

16.800 

21,000 

840 
6£ 

560 

26.7 
29.2 

26.7 

1  120 

840 
840 

670 

420 

525 

21 
17 
14 

7 
7 

840 
1050 

42 

11 

7-5 

7 

1260 
1570 

63 
5i 
42 

9 

8.2 

1680 
2  IOO 

a 

55 

10  5 
9-5 

2100 
2625 

105 
85 
70 

11.6 
10.5 
9-5 

210 

105 

o°5 

85 

2520 
3*50 

126 
1  02 

84 

12.7 

"•5 
10.4 

1  68 
126 
126 

IO2 

28 

21 
21 
»7 

56 
42 
42 

33 

in  ON  O\  00 

no 

84 
84 
68 

Net  area  ventilating  register  . 

*  This  quantity  is  (defined  page  272). 
f  For  pitch  of  one  inch  per  foot.     Use  larger  pipe  for  less  pitch- 

NOTE. — The  proportions  in  the  above  table  agree  very  well  with  those  given 
by  the  Excelsior  Steel  Furnace  Co.  for  the  condition  of  changing  the  air  in  each 
room  four  times  per  hour,  which  can  be  taken  as  representing  the  average 
amount  required  to  bring  in  the  heat. 

The  grate  surface  is  computed  for  combustion  of  3  pounds  per  square  foot 
per  hour,  with  an  efficiency  of  70  per  cent,  or  a  greater  amount  at  less  efficiency. 
The  heating  surface  given  in  above  table  is  much  larger  than  ordinarily  found 
in  furnaces,  but  not  too  large  for  best  results. 

142.  Air-supply  for  the  Furnace. — The  air-supply  for  the 
furnace  is  usually  obtained  by  the  construction  of  a  passage- 
way or  duct  of  wood,  metal,  or  masonry  leading  from  a  point 
beneath  the  furnace  casing  or  near  its  bottom  to  the  outside 


£ 

\ 

COLD  AIR  DUCT 

If 

FIG.  208. — HOT-AIR  FURNACE  WITH  COLD-AIR  Box  BELOW  CELLAR  BOTTOM. 

air,  essentially  as  shown  in  section  Fig.  208.     This  duct  or  pipe 
is  usually  termed  the  cold-air  box  and  is  often  constructed  of 


276  HEATING   AND    VENTILATING   BUILDINGS. 

wood.  In  all  cases  there  should  be  a  screen  over  the  outer 
end  to  keep  out  vegetable  matter  or  vermin,  and  doors  should 
be  arranged  so  that  it  can  be  cleaned  periodically.  A  damper 
is  usually  desirable,  arranged  so  that  it  can  be  partly  or  entirely 
opened  to  regulate  the  admission  of  the  cold  air.  The  cold- 
air  box  should  be  made  perfectly  tight  and  in  a  workmanlike 
manner,  so  that  air  cannot  escape 'into  or  be  drawn  from  the 
cellar  or  basement.  This  should  join  onto  the  furnace  casing 
at  as  Iowa  point  as  the  character  of  the  cellar  bottom  will  per- 
mit. In  some  instances  it  is  desirable  to  erect  two  cold-air 
boxes,  opening  to  the  air  on  opposite  sides  of  r.he  house,  so 
that  the  supply  may  be  drawn  from  either  direction  as  re- 
quired to  obtain  the  help  of  wind-pressure,  to  aid  in  the  cir- 
culation of  the  air  over  the  furnace. 

The  cross-sectional  area  of  the  cold-air  box  is  proportioned, 
by  different  authorities,  from  66  t^o  100  per  cent  of  the  sum,  of 
the  areas  of  all  pipes  taken  from  the  furnace.  If  this  were 
proportioned  so  that  its  area  should  be  in  ratio  to  the  re- 
spective volume  of  cold  and  heated  air,  the  sectional  area  of  the 
cold-air  box  should  be  about  80  per  cent,  of  the  sum  of  the 
areas  of  the  various  stacks.  To  avoid  frictional  resistances  it 
would  seem  to  be  advisable  when  practicable  to  make  its  area 
equal  to  that  of  the  sum  of  the  areas  of  the  stacks. 

143.  Pipes  for  Heated  Air. — The  pipes  for  heated  air  are 
of  two  classes  :  first,  those  which  are  nearly  horizontal  anol  are 
taken  from  near  the  top  of  the  furnace  casing — these  are 
usually  round  and  made  of  a  single  thickness  of  bright  tin, 
and  if  possible  erected  with  an  ascending  pitch  of  one  inch  to 
one  foot,  and  are  termed  leader-pipes ;  second,  rectangular  verti- 
cal pipes  or  risers,  termed  stacks,  made  in  such  dimensions  as  will 
fit  in  the  partitions  of  a  building  and  to  which  the  leader-pipe 
connects.  The  bottom  of  the  stack  is  enlarged  into  a  chamber 
termed  a  boot,  which  is  made  in  various  forms  and  provided 
with  a  round  collar  for  connection  to  the  leader-pipe.  The  top 
part  of  the  stack  may  be  provided  with  a  similar  boot  from 
which  horizontal  rectangular  stacks  are  taken,  or  it  may  be 
connected  to  a  rectangular  chamber  into  which  the  register 
may  be  fitted  and  which  is  known  as  the  register  box.  The 
stacks  usually  pass  up  or  near  the  woodwork  of  partitions, 


HEATING   WITH  HOT  AIR. 


277 


and  for  lessening  the  fire  risk  as  well  as  preventing  loss  of  heat 
should  be  made  with  double  walls  separated  by  an  intervening 
air-space.  The  register  boxes  should  also  in  every  case  have 
double  walls.  The  general  form  of  a  stack  in  position  in  a 
partition,  with  boot  attached  at  bottom  for  leader-pipe  and  with 
round  connection  for  register  box,  is  shown 
o  in  Fig.  209. 

The  leader-pipes  and  stacks,  boots,  and 
^  register  boxes  are  now  a  standard  article 
of  manufacture  by  several  firms.  I  am 
o  indebted  to  the  Excelsior  Steel  Furnace 
^  Company  of  Chicago  for  the  table  of 
<  capacity  and  dimensions  of  various  forms 
^  of  stacks  and  leader-pipes,  given  on  page 


a  It   will    be   found    profitable    in    nearly 

<      every  case   to  wrap   the  leader-pipes  with 
£      two  or  more  thicknesses  of  asbestos  paper 


t 

u  FIG.     2  TO.  —  FIRST-FLOOR     OUTSIDE 

£  REGISTER  Box  WITH    COLLAR  AT- 

TACHED. 

and  mineral  wool  in  order  to  prevent  loss  of  heat.  It  is 
desirable  to  locate  the  stacks  in  the  inside  partition-walls 
of  the  building,  or  where  they  will  be  protected  as  much 
as  possible  from  loss  of  heat,  since  any  loss  affects  the  rapidity 
of  circulation.  It  is  generally  necessary  to  have  the  leader- 
pipes  not  over  15  feet  in  length,  otherwise  the  circulation 
will  be  uncertain  in  amount  and  character. 


278 


HEATING   AND    VENTILATING   BUILDINGS. 


144.  The  Areas  of  Registers  or  Openings  into  Various 
Rooms. — Registers  are  made  regularly  in  various  forms,  square 
or  round,  and  arranged  for  use  either  in  the  floor  or  side  walls 

*  TABLE  OF  SIZES  AND  DIMENSIONS  OF  SAFETY  DOUBLE  HOT- 
AIR  STACKS. 


Stack  as  Listed. 
(In  Inches.) 

Size  of  Outside  Stack. 

Size  of  Inside  Stack. 

f  Inside  Stack  in  Inches 

ty  as  compared  with  that 
ot-air  Pipe  with  Pitch  of 
h  to  i  Foot. 

0 

£"5 

3   •" 
C"*-, 

•S-g 
C  •  - 

f  Round  Pipe  which 
Id  be  ased  with  each 
c. 

f  said  Round  Pipes  in 

ES. 

Registers  and  Register 
:s  which  should  be  used 
each  Stack. 

Feet  of  Space  (approxi- 
)  that  can  be  Heated 
each  Stack  with  Pipe 
Registers  of  size  given. 

ilent  of  said  Space  on 
r  of  Rooms  10  Ft.  high. 

i  Inches  of  Registers 
Space  occupied  by 
deducted. 

«4^ 

*e3 

*rt 

0 

*O  HE    r^ 

^    —  -*-> 

0   3y 

OJ3 

O    X  •** 

a>  r^ 

>  ° 

,~  jq    C/5 

V 

1 

3 

OJ 

cLvi-1" 

•J3--  O 

ui  O  rt 

^  °'fe 

^  g-r'c 

.-  O 

rt-^  c5 

< 

* 

1 

O 

^?t 

•J5 

1" 

i/5 

u 

w^ 

< 

4x    8 

3%x    7% 

|3MX    7 

23 

35 

6»4 

7 

38 

6x    8 

500 

6x    8 

35 

4X 

3%  x    9% 

3Hx    9 

29 

8 

5» 

8x  10 

850 

8x  10 

45 

4x 

3%  x  10% 

314x10 

48 

8 

8 

5° 

8x  12 

IOOO 

9x11 

55 

4X 

SZ  X  T  1^ 

3^x11 

35 

53 

8)4 

9 

63 

yx  12 

1250 

IOX  12^ 

60 

4  x    - 

3%x  *3% 

3^x13 

41 

63 

9 

9 

63 

1O  X  12 

1650 

12  X  14 

70 

6x 

5*^  x    9^^ 

5^4  x    9 

47 

71 

10 

10 

78 

10  X  14 

2000 

I2XI7 

80 

6x 

5%  x  11% 

5/4  x  1  1 

58 

87 

ii 

12 

"3 

12x15 

2300 

14X17 

TI5 

6x  14 

5%xi3% 

5^4  x  13 

68 

102 

12 

12 

113 

12  X  17 

14  x  20 

2000 

OQOO 

I5XI8 

1  20 

Teg 

8x18 

7%  x  17% 

7^x17 

79 

124 

1  86 

15 

16 

201 

16  x  24 

JUOU 

4000 

20X20 

150 

210 

10  x  20 

9%  x  19% 

9J4  x  19 

i76 

264 

18 

18 

254 

20x24 

5400 

20  x  27 

270 

10  X  24 

9%X23% 

9^x23 

213 

330 

20^ 

20 

3M 

21  X  29 

7000 

20X35 

340 

Stacks  for  4  inch  studs  carried  in  stock.     Other  sizes  made  to  order. 
*  This  table  is  copyrighted  by  Excelsior  Steel  Furnace  Co. 

as  required.     These  registers  are  usually  supplied  with  a  series 
of   valves   which    may   be    readily   opened    or   closed.      The 


FIG.  211. — REGISTER  BOXES  SHOWN  IN  POSITION. 

space  taken  by  the  screen  and  valves  is  usually  about  J  of  that 
of  the  register,  so  that  the  effective  or  net  area  is  about  |  of 


HEATING   WITH  HOT  AIR.  2/9 

the  nominal  size  of  opening.  These  registers  may  be  ob- 
tained finished  in  black  or  white  japan,  or  electroplated  with 
nickel,  brass,  bronze,  or  copper.  The  table  on  page  280  gives 
the  various  sizes  of  registers  which  are  regularly  on  the  market, 
their  effective  area  in  square  inches,  and  diameters  of  round 
pipe  having  the  same  capacity. 

The  areas  of  stacks  may  be  considerably  less  than  these 
of  the  registers,  since  it  is  generally  required  that  the  velocity 
of  air  entering  the  room  shall  not  exceed  3  or  4  feet  per 
second,  while  that  passing  through  pipes  and  stacks  may  have 

;  the  highest  velocity  possible,  which  for  the  different  floors  will 
not  differ  greatly  from  4  to  6  feet  per  second,  as  already  ex- 

\  plained.     For  methods  of    proportioning  ventilating  flues  see 

\  page  233. 


(Fie.  212. — SIDE- WALL  REGISTER  HEAD  OR  FLANGE. 
Considerable  difference  of  opinion  exists  as  to  the  relative 
merit  of  floor  and  wall  registers  for  heating  purposes.     It  is 
!   the  common   practice  to  use  floor  registers  for  most  rooms  on 
I  the  first  floor,  and  wall  registers  for  rooms  on  the  second  and 
I  higher  floors.     The  floor  register,  from  its  general  form  and 
i   position,  can  be   supplied  with  hot  air  somewhat  more   readily 
I  than   the  wall  register,  and  for  that   reason  may  induce  some- 
I  what  stronger  circulation,  but  it  is  a  receptacle  for  dust  and 
h  sweepings  of  the  room  and  in  a  position  to  materially  interfere 
with  the  carpets.     It  will  be  found  that  the  experiments  made 
by  Briggs  (see    page  46)  as   to  diffusion  of  air  hold   in  the 
case  of   furnace   heating  the    same   as  in   that  of  any  other 


280 


HEATING   AND    VENTILATING   BUILDINGS. 


system.  From  these  experiments  it  would  seem  that  the 
highest  efficiency  would  be  attained  when  the  inlet  for  the 
heated  air  was  at  the  side  near  the  top  of  the  room  and  the 
outlet  for  ventilation  near  the.  floor.  This  distribution  is  one 
that,  so  far  as  the  writer  knows,  has  never  been  practised  in 
furnace  heating  of  residences,  although  it  is  the  commonly 
accepted  method  in  school-house  heating,  whether  with  a 
furnace  or  an  indirect  system  of  steam  or  hot-water  heating. 

TABLE  OF  REGISTERS. 


Size  of 
Opening. 
Inches. 

Effective 
Area.  Square 
Inches. 

Diameter 
Round  Pipe. 
Inches. 

Size  of 
Opening. 
Inches. 

Effective 
Area.  Square 
Inches 

Diameter 
Round  Pipe. 
Inches. 

4^  X     6* 

20 

5-  ! 

10  X   20 

132 

13.0 

4X8' 

21 

5.2 

12   X   12 

96 

II.  I 

4     X  10 

26 

5-8 

12   X    14 

112 

11.9 

4     X  13 

34 

6.6 

12   X    15 

120 

12.4 

4     X  15 

40 

7.2 

12   X    16 

128 

12.8 

4     X  18 

48 

7.8 

12   X    17 

136 

13-2 

6X6 

24 

5-6 

12   X    18 

144 

13  5 

6     X     8 

32 

6.4 

12  X    19 

152 

13.9 

6X9 

36 

6.7 

12   X    20 

1  60 

14-3 

6     X  10 

40 

7-2 

12    X   24 

192 

15-6 

6     X  14 

56 

8-5 

14  X  14 

130 

12.8 

6     X  16 

64 

9.1 

14  X  16 

149 

14.8 

6     X  18 

72 

9.6 

14  X  18 

168 

14.7 

6     X  24 

96 

n.  i 

14   X    20 

186 

15-5 

7X7 

32 

6.4 

14   X    22 

205 

16.2 

7     X  10 

52 

8.2 

15  X  25 

250 

17.8 

8X8 

42 

7-4 

16  X  16 

170 

14.7 

8     X  10 

53 

8.2 

16  X  20 

213 

16.5 

8     X  12 

64 

9.6 

16  X  24 

256 

iS.i 

8     X  15 

80 

IO.  I 

18  X  24 

288 

19.2 

8     X  18 

96 

II  .2 

20   X    20 

267 

18.5 

9X9 

54 

8.2 

20   X    24 

320 

20.2 

9     X  12 

72 

9.6 

20   X    26 

347 

21  .O 

9    X  13 

78 

IO.O 

21    X    29 

406 

22.7 

9     X  14 

84 

10.3 

24  X  24 

384 

22.1 

10  X  10 

66 

9.2 

24  X  32 

512 

25-5 

10    X    12 

80 

9.1 

27  X  27 

486 

25.0 

10  X  14 

93 

10.9 

27  X  38 

684 

29-5 

10  X  16 

107 

ii.  7 

30  x  30 

600 

27.7 

10  X  18 

120 

12.4 

145.  Circulating  Systems  of  Hot  Air.  -By  connecting  the 
cold-air  box  with  the  hall  floor  or  the  lower  portion  of  a  pas- 
sage communicating  with  all  rooms  of  the  building  and  clos- 
ing outside  connections  a  downward  current  of  air  will  pass 
from  the  rooms  to  the  furnace,  which,  being  warmer  than  the 
outside  air,  will  aid  materially  in  heating.  Such  a  connection 


HEATING    WITH  HOT  AIR.  28 1 

if  properly  made  and  used  with  judgment   may  be  of  great 
^service   in   reducing  the   cost  of  operation  without   seriously 
^affecting  the  ventilation.     Such  a  system  if  erected,  however, 
should  be  supplied  with  devices  to  prevent  overheating  and 
arranged  so  that  cold  air  can  be  drawn  from   outside  of  the 
building  whenever  desired.     There    is  so  much  danger  that 
ventilation  will  be  poor  with  this  system  that  it  is  not  recom- 
mended. 

146.  Combination  Heaters. — A  combination  heater  con- 
sisting of  a  hot-air  furnace,  with  the  addition  of  a  boiler  for 
hot  water  or  steam,  is  meeting  with  somewhat  extensive  use 

'and  has  been  described  on  page  189  so  far  as  relates  to  the 
construction  of  the  steam  and  hot-water  appliances.  In  case 
a  combination  heater  is  used  the  area  of  the  grate  and  heating 
surfaces  will  need  to  be  proportioned  for  both  systems.  A  com- 
bination heater  is  better  suited  to  large  buildings  than  a  hot-air 
furnace.  In  practice,  however  it  will  be  found,  diffic.  it  to  so 
proportion  the  amount  of  heating  and  radiating  surface,  as  to 
give  a  perfect  distribution  of  heat  in  rooms  some  of  which  are 
heated  with  hot  water  or  steam,  and  some  with  hot  air,  but 
this  difficulty  will  no  doubt  be  largely  overcome  by  experience. 

147.  Heating  with  Stoves  and  Fireplaces. — The  manu- 
facture of  stoves  for  heating  purposes  is  a  very  great  industry 
in  the  United  States  and  they  are  extensively  used  in    the 
cheaper  classes  of  dwellings.    In  every  case  the  stove  is  located 
directly  in   the  room  to  be  heated  and  is  connected  with  a 
chimney  by  means  of  several  lengths  of  sheet-iron  pipe.    Stoves 
are  built  in  many  forms,  some  of  which  are  very  elaborate  and 
highly  ornamented,  and  in  many  cases  they  are  provided  with1 
magazines  from  which  the  coal  feeds  itself  automatically  as  re- 
quired.    The  heat,  given  off  from  a  stove,  is  generally  nearly 
all  utilized  in  warming,  perhaps  not  over  10  or   15   per  cent 
being  carried  off  by  the  chimney.     Stoves  do  not,  however, 
present  an  economical  mode  of  heating,  largely  because  the 
wastes  which  occur  from  the  operation  of  small  fires  are  very 
great  and  cannot  be  avoided.     It  is  doubtful  if  the  efficiency 
averages   much  above  25  per   cent.      In  addition,  the   stove 
occupies   useful  room,  is   the  source  of  very  much  dirt  and 
litter,  and  requires  a  great  deal  of  attention.' 


282  HEATING   AND    VEN7ULATING   BUILDINGS. 

Open  fireplaces  which  were  used  at  one  time  extensively 
are  very  wasteful,  as  little  more  than  the  direct  radiant  heat 
from  the  fire  is  absorbed  in  warming.  They  are  also  subject 
to  all  the  wastes  which  pertain  to  stoves,  and  their  probable 
efficiency  cannot  be  considered  as  over  15  or  20  per  cent. 
They  are,  however,  valuable  adjuncts  of  a  system  of  ventila- 
tion, since  large  quantities  of  air  are  drawn  from  the  room  and 
discharged  into  the  chimney.  In  the  use,  of  a  stove  called  a 
fireplace  heater,  the  heated  gases  from  an  open  fire  pass  through 
a  drum  or  radiating  surface  in  the  room  above,  and  the  heat 
which  otherwise  would  be  discharged  from  the  chimney  and 
wasted  is  partly  utilized  in  heating. 

148.  General  Directions  for  Operating  a  Furnace. — The 
general  directions  for  operating  a  furnace  so  far  as  regards  the 
care  of  the  fire  are  the  same  as  those  which  have  been  previ- 
ously given  for  the  operation  of  steam-heating  furnaces,  page 
169  ;  there  are,  however,  no  steam-gauges  or  safety  appliances 
'needed.  In  regulating  the  temperature  of  the  house  the 
drafts  of  the  furnace  should  be  operated  rather  than  the  valves 
of  registers  leading  to  various  rooms.  In  some  instances  if  the 
circulation  is  strong  in  certain  directions  and  weak  in  others  so 
that  certain  rooms  cannot  be  heated,  it  may  be  a  good  plan  to 
shut  all  registers  except  the  one  to  the  room  where  heat  is 
required  until  circulation  is  established,  after  which,  circulation 
will  usually  continue  without  further  attention.  In  the  opera- 
tion of  a  furnace  great  care  should  be  taken  that  the  metal 
never  becomes  red  hot  or  even  cherry-red.  If  it  will  not  warm 
the  building  without  being  excessively  hot,  the  furnace  is  too 
small,  or  else  has  too  little  radiating  surface  in  proportion  to 
the  fire-pot.  The  water-pan  should  be  kept  filled  with  water. 
Thermostats  arranged  to  open  or  close  the  drafts  when  desired 
are  in  use  in  many  systems  of  furnace  heating  with  success. 

For  protection  of  the  furnace  during  summer  months  some 
makers  recommend  that  the  fire-pot  be  filled  with  lime.  For 
burning  soft  coal,  furnaces  of  special  construction  only  should 
be  employed. 

NOTE. — Rules  for  Furnace  Heating  : 

First.  To  find  area  of  grate  in  square  inches:  Divide  total  window 
surface  plus  \  total  exposed  wall  surface  in  square  feet  by  200. 

Second.  To  find  area  of  flue  for  any  room  in  square  inches:  Divide 
window  surface  plus  \  wall  surface  in  square  feet  by  1.2  for  first  floor,  by 
1.5  for  second  floor,  by  1.8  for  third  floor. 


CHAPTER    XIII. 
FORCED-BLAST  SYSTEMS  OF  HEATING  AND  VENTILATING. 

149.  General  Remarks. — In  the  systems  of  hot-air  heat- 
ing which  have  been  described  the  circulation  of  air  is  caused 
:>y  expansion   due   to  heating,  which  is  a   feeble  force  and  is 
ikely  to  be  overcome  by  adverse  wind  currents,  by  badly  pro- 
portioned pipes,  or  by  friction  ;  by  employing  a  fan  or  blower 
of  some  character  for  moving  the  air  the  circulation  will  be 
rendered  positive  and  so  strong  as  to  be  unaffected  by  these 
causes. 

This  system  can  be  employed  where  power  is  available,  and 
n  many  cases  will  be  found  to  present  an  economical  and  satis- 
'actory  system  of  heating,  comparing  well  with  any  that  has 
jeen  devised,  especially  when  the  amount  of  ventilation  pro- 
vided is  considered.  The  cost  of  heating  a  large  quantity  of 
air  is,  however,  in  every  case  one  of  considerable  amount,  so 
that  it  is  quite  probable  that  in  expense  of  operation  no  sys- 
tem of  indirect  heating,  whether  by  furnace  or  steam-pipes, 
can  compare  with  that  of  direct  hot-water  or  steam  radiation. 
The  systems  of  forced-blast  heating  are  in  almost  every  case 
employed  in  connection  with  steam-heated  surfaces,  but  in 
some  instances  the  system  has  been  applied  successfully  with 
furnace  heated  surfaces.* 

150.  Form  of  Steam-heated  Surface. — The  heating  sur- 
face is  generally  built  of  inch  pipe,  set  vertically  into  a  square 
cast-iron  base,  connected  at  top  with  return-bends,  although 
the  box  coil,  Fig.  94,  page  109,  or  any  form  of  indirect  radiat- 
ing surface  could  be  used.     The  fan  or  blower  is  placed  either 

*  The  Metal  Worker,  May  25,  1895,  gives  an  interesting  example  showing 
the  successful  use  of  a  blower  and  furnace  for  heating  a  church. 

283 


284  HEATING   AND    VENTILATING   BUILDINGS. 

so  as  to  draw  the  air  by  suction  over  the  heated  surface  and 
then  deliver  by  pressure  into  the  rooms,  or  it  is  placed  so  as  to 
force  the  air  by  pressure  over  the  heating  surface  and  thence 
into  the  conduits  leading  to  the  various  rooms.  The  heating 
surface  is  usually  surrounded  with  metallic  walls  forming  a 
chamber  through  which  the  air  is  discharged.  Fig.  213  shows 
the  arrangement  often  adopted,  in  which  a  pressure  fan  is 
directly  connected  to  an  engine,  and  arranged  to  take  air  from 


FIG.  213. — BLOWER  CONNECTED  TO  ENGINE. 

the  atmosphere  and  force  it  into  the  chamber  in  which  the 
heating  surface  is  placed. 

151.  Ducts  or  Flues— Registers.* — The  dimensions  of  the 
ducts  or  flues  leading  from  the  heater  should  be  such  that  the 
required  amount  of  air  may  be  delivered  with  a  low  pressure 
and  velocity,  so  as  to  avoid  excessive  resistances  due  to  friction. 
The  velocity  which  will  be  produced  by  various  pressures  in 


*  General  formulae  for  the  motion  of  air  in  long  pipes  is  to  be  found  in 
Weisbach's  Mechanics,  and  in  article  Hydrodynamics  in  Encyclopaedia  Britan- 
nica,  by  Prof.  W.  C.  Umvin.  The  formula  given  by  Weisbach  is  elaborated  in 
an  article  by  Carl  S.  Fogh  '^Engineering  Record,  Feb.  16,  1895,  and  a  graphical 
diagram  given  for  practical  application.  The  uncertainty  which  relates  to  the 
application  of  these  elaborate  formulae  is  well  shown  by  the  fact  that  a  factor  of 
safety  of  4  is  used  by  Mr.  Fogh,  and  serves  in  the  writer's  opinion  to  render 
such  estimates  as  crude  as  those  obtained  by  the  approximate  formulae  given 
here.  The  article  is  of  great  value,  however,  to  those  desiring  to  study  the 
theory  of  motion. 


FORCED-BLAST  SYSTEMS.  285 

excess  of  that  of  the  atmosphere  is  given  in  table  on  page  42, 
from  which  it  is  seen  that  a  pressure  sufficient  to  balance  ^ 
inch  of  water  (0.29  ounce  per  square  inch)  will  produce  a  ve- 
locity of  30  feet  per  second  in  a  pipe  100  feet  long  and  I  foot 
in  diameter ;  this  is  generally  considered  to  be  the  maximum 
velocity  which  should  be  pemitted  in  any  of  the  pipes  or  pas- 
sages. In  proportioning  apparatus  in  this  system  of  heating 
it  is  generally  required  that  sufficient  air  shall  be  brought  in 
to  change  the  cubic  contents  of  the  room  four  times  per  hour. 
By  consulting  the  table  on  page  53,  it  will  be  seen  that  for  this 
condition,  and  without  allowance  for  friction,  it  will  require  a 
flue  with  5.7  square  inches  of  area  for  each  1000  cubic  feet  of 
space  in  the  room.  By  adding  two  inches  to  the  diameter 
obtained  as  above,  a  fair  allowance  for  friction  will  be  made. 

The  pipes  are  usually  made  of  galvanized  iron  or  bright  tin 
and  should  have  tight  joints  and  be  protected  from  loss  of  heat 
by  some  good  covering  (see  page  197).  Flues  of  brick  or 
masonry  cause  more  friction  than  those  of  galvanized  iron,  and 
if  used  should  generally  be  about  two  inches  larger  in  diameter 
than  provided  for  by  this  table.  As  branch  pipes  for  various 
apartments  are  taken  off,  the  main  pipe  can  be  reduced  in  size  ; 
this  should  never  be  done  abruptly,  but  only  by  the  use  of  taper- 
ing tubes,  the  angle  of  whose  sides  measured  from  the  line  of 
the  main  pipe  should  rarely  be  greater  than  15  degrees.  The 
fan  can  be  located  in  a  chamber  which  is  connected  with  the 
external  air,  as  in  Fig.  214,  or  it  may  be  placed  in  a  tube  or 
passageway  leading  from  the  heating  surface  .to  the  out- 
side. 

The  area  of  the  cold-air  duct  or  passageway  leading  to  the 
fan  should  be  as  great  as  possible  in  order  to  keep  the  velocity 
of  entering  air  low ;  if  the  area  of  cross-section  is  equal  to  the 
sum  of  the  areas  of  all  the  ducts  leading  from  the  heating  surface, 
i  the  velocity  will  probably  be  about  three  quarters  of  that  in 
the  hot-air  pipes,  and  may  draw  in  considerable  dust  and  dirt 
from  outside.  The  flues  which  convey  air  to  the  rooms  should 
discharge  near  the  upper  part  of  the  room  substantially  as 
described  on  page  49  and  shown  in  Fig.  21.  The  friction  in 
small  pipes  is  greater  than  in  large  ones,  being  relatively  pro- 
portional to  the  circumference  or  perimeter ;  hence  the  sum 


286 


HEATING   AND    VENTILATING   BUILDINGS. 


of  the  areas  of  the  branch  pipes  should  be  considerably  greater 
than  that  of  the  main.* 

The  table  on  opposite  page  gives  the  number  of  small  pipes 
which  provide  an  area  equivalent  to  that  of  one  large  pipe  of 
similar  cross-section  ;  in  case  no  table  is  at  hand  the  same  re- 
sults may  be  obtained  by  dividing  the  larger  diameter  by  the 
smaller  one  and  taking  the  square  root  of  the  fifth  power  of  the 
quotient. 

The  following  table  gives  the  actual  amount  discharged 
with  constant  resistance,  and  with  pressure  equal  to  one  half 
inch  of  water  column  in  round  pipes,  as  computed  from  Unwin's 
formulae,  page  41  : 

VELOCITY  AND  QUANTITY  OF  AIR  DELIVERED  IN  PIPES  OF 
DIFFERENT  DIAMETERS,  EACH  100  FEET  LONG,  WITH  AN 
AIR-PRESSURE  EQUAL  TO  \  INCH  OF  WATER  COLUMN. 


Diameter  of 
Pipe.    In. 

Velocity  of  Air. 
Ft.  per  Sec. 

Cubic   Feet    of 
Air  per  Min. 

Diameter  of 
Pipe.    In. 

Velocity  of  Air. 
Ft.  per  Sec. 

Cubic    Feet   of 
Air  per  Min. 

I 

8.7 

2.6 

16 

35  6 

3,024 

2 

12.4 

16 

18 

36.8 

4,032 

3 

15-0 

45 

20 

38.8 

5,184 

4 

17.3 

90 

22 

40.6 

6,480 

5 

19.4 

1  60 

24 

42.4 

8,208 

6 

21.3 

253 

26 

44-2 

9»y36 

7 

23  o 

380 

28 

46.0 

U,952 

8 

24-5 

5*5 

30 

47-4 

14.256 

9 

26.1 

720 

36 

52.0 

23,040 

10 

27.4 

900 

42 

56.1 

33-120 

ir 

28.6 

1190 

48 

61.0 

46,080 

12 

30.5 

1440 

54 

63.6 

61,920 

13 

31-3 

1620 

60 

67.0 

80,640 

14 

32-4 

2160 

*The  velocity  of  flow  of  air  is  given  in  formulae  on  page  41 ;  the  amount 
discharged  is  equal  to  the  area  of  the  pipe  multiplied  by  the  velocity,  and  will 
be  equal  in  every  case  to  the  square  root  of  the  fifth  power  of  a  constant  multi- 
plied by  the  diameter  of  the  pipe.  If  we  denote  diameter  of  larger  pipe  by 
of  smaller  pipe  by  d,  and  the  number  of  smaller  pipes  required  to  make  one  of 
area  equivalent  to  that  of  larger  by  n, 


To  find  diameter  of  round  pipe,  d,  which  shall  be  equivalent  in  carrying  capacity 
to  a  rectangular  pipe  with  dimensions  a  and  b,  we  would  have 


-  I/   32< 
V  X\a 


-f  b} 


FORCED-BLAST  SYSTEMS.  2&? 


*        =  cx 


com  -coo 

co  ~  M*  M  co 


k.               •— 'T3  ^rf*    r^    ~r* 

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^     §|^a'S^ 


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;.. i-iMpaco-^- 


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co  r^  M 


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wcoTj-mr^c>'-''-'«'HpjCMC4c'-r  u->o  t^oo  co  o  co  co   o 


co  co  <-t 

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^^^>•coo  COPI  PIO  "-"co  r>-o^w  Oco   ^mcoco  coir)in-r>-«  o  w  coo^ 
_^_____ —  S  PI  co  -r 


>-ico»r>QO 


o*O  -rr^pi  •->  cor^oo  r^*rio  r^-r-t-Tt-«r>cococo  o^o  *•" 
Mco-i-i-iOO'-'cor^piC>  r^co    s^co   c«->r^oo   —cocoo   — 


288 


HEATING  AND    VENTILATING   BUILDINGS. 


Air  which  is. drawn  in  from  outside  at  high  velocity  is  often 
loaded  with  dust,  and  for  this  reason  filters  made  of  some  tex- 
tile material,,  or  baffle-plates  which  discharge  the  dust  into 
vessels  of  water,  are  sometimes  required  in  the  passageway 
leading  to  the  fan.  Where  fans  are  required  for  ventilation  as 


well  as  heating,  it  is  an  advantage  to  have  by-pass  pipes  lead- 
ing from  the  fan  around  as  well  as  over  the  heating  surface 
and  provided  with  proper  dampers  so  that  the  air  can  be 
delivered  into  the  room  fully  or  partly  heated  as  required. 
Such  an  arrangement  is  shown  in  Fig.  214. 


FORCED-BLAST  SYSTEMS.  289 

The  net  areas  of  registers  should  be  sufficiently  great  to 
prevent  the  velocity  in  the  entering  air  becoming  so  great  as 
to  produce  a  sensible  draft.  Taking  this  limiting  value  at  5 
feet  per  second,  the  area  of  the  register  can  be  obtained  from 
table  on  page  53.  If  the  air  is  to  be  changed  four  times  per 
hour,  there  should  be  34  square  inches  in  the  register  for 
each  1000  cubic  feet  of  space.  The  nominal  area  of  the  regis- 
ter should  be  about  50  per  cent  greater  than  given  by 
this  computation  ;  the  actual  areas  of  commercial  registers  is 
given  in  table  page  280. 

152.  Blowers  or  Fans. — Blowers  or  fans  are  made  in  a 
great  variety  of  forms,  and  there  is  little  reliable  data  as  to  the 
best  shape  of  fan-blades  for  practical  use.  It  is  quite  certain 
that  in  the  centre  of  the  fan  there  is  very  little  useful  work 
done,  and  in  some  cases  a  back  current  is  produced  which 
reduces  the  capacity  of  the  fan,  although  probably  not  affect- 
ing to  any  great  extent  the  power  required  to  drive  it.  It  is 
quite  probable  that  the  workmanship  and  character  of  bear- 
ings have  more  to  do  with  the  efficiency  than  any  theoretical 
form  of  blades.  The  limits  of  this  book  do  not  permit  a  dis- 
cussion of  the  various  forms  of  blowers.  The  reader  is  referred 
for  some  experiments  on  this  subject  to  the  work  on  "  Warm- 
ing and  Ventilating  of  Buildings,"  by  J.  H.  Mills,  vol.  II,  page 

559- 

The  motive  power  employed  to  drive  fans  may  be  obtained 

from  a  running  countershaft,  from  an  engine  either  directly 
connected  or  belted,  or  from  an  electric  or  water  motor.  Where 
the  fan  is  to  be  used  only  at  intervals,  the  electric  motor  will 
be  found  more  desirable  and  fully  as  economical  as  the  engine. 

The  fan  should  be  located  in  a  position  where  the  noise 
caused  by  its  operation  is  likely  to  be  of  little  importance, 
and  it  should  be  arranged  so  that  a  portion  or  all  of  the  blast 
can  be  deflected  from  the  heating  surface  and  sent  to  the 
rooms  without  being  warmed  if  so  required.  This  can  be  done 
by  proper  construction  of  ducts  and  dampers. 

The  actual  power  required  to  drive  fans  cannot,  for  the 
reasons  mentioned,  be  determined  from  theoretical  considera- 
tions, but  must  be  obtained  by  actual  test  for  each  given  make 
of  fan. 


290 


HEATING   AND    VENTILATING  BUILDINGS. 


The  following  table  gives  the  sizes,  capacity,  and  power  re- 
quired for  various  dimensions  of  the  Sturtevant  pressure  fan- 
wheels,  which  are  built  to  be  set  in  wood  or  brick  housing : 

TABLE   OF   CAPACITIES,    REVOLUTIONS    PER    MINUTE,    AND 
HORSE-POWER  REQUIRED. 

PRESSURE  IN  OUNCES  PER  SQUARE  INCH,  AND  INCHES  OF  WATER. 


Size. 
In. 

Diameter  Fan 
in  inches. 

O  o 

a 
Q 

Width  of  housing 
in  inches. 

Pulley. 

i  oz.  Pressure. 
0.43  in. 

i  oz.  Pressure. 

0.86  in. 

J  oz.  Pressure. 
1.3  in. 

i  oz.  Pressure. 
1.73  »n. 

a 

5 

cJ 

U 

£ 

Jfi  C 

_'  c 

"A 

V3  C 

«ti-S 

Cu 

v,  c 

—  0 

&,' 

J"  c 

9'Q 

n'S 

cu 

ffi 

*<i 

OS. 

x}L 

ul 

*i 

uR 

rtS.  Ug. 

56X3* 
7x4 
8x4 

10  x  5 

I2X  6 

14x7 
15x7* 

66 
72 
84 
96 
108 

120 
144 

1  68 

1  80 

47i 
6ol 
68* 

ll> 

I02i 
120 

I28J 

42 
48 
48 
54 
60 
72 
84 
90 

22 
24 

28 

H 
11 
& 

4 

12* 
12* 
12* 
12* 
14* 

14* 
164 

150 
138 

118 
103 

K 

69 
59 
55 

24734 

3l694 
42167 
47486 
60992 
75816 
108703 
149840 
172740 

1.2 

2.1 

2-3 

3-o 

3-7 
5-3 

1:1 

212 

I94 

166 

MS 
129 
116 

Q7 

% 

34992 

44857 

67218 

86180 
107313 
^3850 

212070 

244487 

3-4 

44 

5-J 

0.6 

8.4 
10.5 
15-0 
20.7 
23-8 

259 
238 
204 
178 
!59 
'43 
119 
1  02 
95 

42892 
54966 
73130 
82355 
105602 
T3'475 
188520 
259765 
299584 

5-6 
7-1 
9-5 
10.8 

17.1 

24-5 
33-8 
39-o 

300 

206 
183 
165 

3 

no 

49524 
63463 
84436 
95086 
121938 
151800 
217340 
300000 
3459oo 

9-7 

T2.4 

18.6 

23.8 

29.6 

42.4 
58.4 
67-4 

The  following  table  gives  the  capacity  and  power  required 
for  Sturtevant  steel-plate  exhaust  fans : 

TABLE   OF   CAPACITIES,    REVOLUTIONS    PER   MINUTE,    AND 
HORSE-POWER  REQUIRED. 

PRESSURE  IN  OUNCES  PER  SQUARE  INCH  AND  INCHES  OF  WATER. 


J  oz.  Pressure. 

*  oz.  Pressure. 

i  oz.  Pressure. 

i  oz.  Pressure. 

0.43  in. 

0.86  in. 

1.3  »n. 

1.73  in. 

Size. 

Rev. 

Cub.  ft. 

Ou 

Rev. 

Cub.  ft. 

cu 

Rev. 

Cub.  ft. 

DH 

Rev. 

Cub.  ft. 

• 

per 

per 

per 

per 

per 

per 

per 

per. 

. 

min. 

mm. 

ffi 

min. 

min. 

S* 

mm. 

mm. 

DC 

mm. 

min. 

a 

40  in. 

412 

2,388 

.11 

582 

3,380 

•  32 

714 

4,141 

•54 

824 

4,782 

•93 

50  in. 

329 

4,396 

.20 

465 

6,220 

.60 

571 

7,623 

.98 

659 

8,802 

1.70 

60  in. 

274 

6,458 

•31 

388 

9,140 

.89 

476 

11,200 

1.49 

549 

12,932 

2  .  52 

70  in. 

235 

8,412 

.41 

333 

1  1  ,  906 

1.16 

407 

14,588 

1.90 

470 

16,848 

3-  29 

80  in. 

206 

11,234 

•54 

291 

15,9001.55 

366 

19.483 

2-53 

412 

22,495 

go  in. 

183 

15,195 

•  74 

258 

21,507  2.10 

317 

26,354 

3-43 

366 

30,427 

5-  92 

100  in. 

165 

19,646 

•95 

233 

27,804 

2.71 

286 

34,070 

4.44 

329 

39,338 

7-67 

An  examination  of  this  table  will  show  the  superior  economy 
of  moving  a  given  volume  of  air  under  low  pressure  with  a  large 
fan  as  compared  with  the  movement  of  the  same  volume  under 
high  pressure  by  a  small  fan.  Thus  to  move  8400  cubic  feet 
of  air  we  can  use  (see  above  table)  a  fan  70  inches  in  diameter 


FORCED-BLAST  SYSTEMS.  2QI 

revolving  at  235  revolutions,  and  requiring  0.41  horse-power  to 
drive  it,  or  we  can  use  a  5o-inch  fan  moving  at  659  revolutions 
and  requiring  1.7  horse-power.  It  is  therefore  evident  that 
true  economy  can  be  best  attained  by  purchasing  a  large  fan, 
and  thereby  saving  the  running  expense  necessary  for  ad- 
ditional power  to  drive  a  smaller  fan  up  to  the  same  capacity. 

An  exhaust  fan  in  the  ventilating  shaft  has  been  used,  in 
some  instances  with  good  results,  for  removing  air  from  a 
building  and  producing  circulation  over  the  heater,  but  there  is 
liability  of  leakage  or  infiltration  of  air  into  the  flues  from  the 
outside.  In  case  air  enters  this  without  passing  over  the  heat- 
ing surface,  which  is  likely  to  reduce  its  efficiency,  so  that  in 
practice  it  has  not  proved  as  satisfactory  as  the  pressure-sys- 
tem. For  purposes  of  ventilation  only,  or  for  the  removal  of 
foul  and  noxious  gases  where  the  ventilating  ducts  are  tight, 
or  as  an  accessory  to  the  pressure-system,  the  exhaust  fan  is 
very  efficient  and  often  invaluable. 

153.  Heating  Surface  Required. — The  methods  of  pro- 
portioning the  heating  surface,  will  be  the  same  in  every  par- 
ticular as  those  previously  described  for  indirect  heaters,  page 
211,  and  for  hot-air  furnaces,  page  278.  In  this  case,  however, 
as  the  air  passes  over  the  heating  surfaces  with  considerable 
velocity,  the  amount  of  heat  which  is  given  off  is  many  times 
more  than  that  from  ordinary  radiating  surfaces  in  direct  heat- 
ing. Experiments  have  already  been  quoted  on  page  83  which 
show  that  the  number  of  heat-units  given  off  per  degree  differ- 
ence of  temperature  per  square  foot  of  surface  per  hour  is 
approximately  equal  to  twice  the  square  root  of  the  velocity 
of  the  air  in  feet  per  second  ;  for  a  velocity  of  36  feet  per 
second  this  would  amount  to  12  heat-units.  For  very  cold 
weather  the  difference  of  temperature  between  heating  surface 
and  air  will  be  from  160  to  170  degrees,  and  in  this  case  the 
total  heat  given  off  per  square  foot  will  be  about  2000  heat-units, 
or  the  equivalent  of  that  given  off  in  the  condensation  of  some- 
what more  than  2  pounds  of  steam. 

The  following  general  formula  will  apply  to  this  case : 
Let  T  =  temperature  of  heating  surface,  /  that  of  the  air  of  the 
room,  /'  that  of  outside  air,  /"  that  of  air  leaving  heating  surface,  t\  the 
mean  temperature  of  air  surrounding  heating  surface  =  \(t"  —  /'),  n  = 


292  HEATING   AND    VENTILATING   BUILDINGS. 

number  of  times  air  is  to  be  changed  per  hour  in  the  room,  C  cubic 
contents  of  room,  a  =  coefficient  giving  number  of  heat-units  per 
degree  difference  of  temperature  per  square  foot  per  hour  from  heating 
surface.  We  have,  since  one  heat-unit  is  capable  of  heating  56  cubic 
feet  of  air  one  degree  :  * 

Cubic  feet  of  air  heated  per  hour  =  nC\ 

Heat-units  required  for  warming  this  air  =  ~~j^^"  ~~  *') » 

Square  feet  of  radiation  =  _       . 

If  in  the  above  equations  outside  air  is  zero  and  air  leaving 
heating  surface  is  at  120  degrees,  and  the  air  in  the  room  is 
changed  4  times  per  hour  and  maintained  at  70  degrees,  we  shall 
have  T  —  220,  t'  —  o,  /,  =  60,  n  =  4,  a(T  —  /,)  =  2000,  from 
which  is  deduced  the  following  simple  rules :  First,  the  heat 
required  expressed  in  heat-units  per  hour  is  equal  to  8.6  times 
the  number  of  cubic  feet  in  the  room  ;  second,  the  number  of 
square  feet  of  heating  surface  will  be  equal  to  the  number  of 
cubic  feet  in  the  room  multiplied  by  0.0041.  The  amount 
of  heat  given  off  per  square  foot  of  surface  is  about  6  times 
that  in  direct  heating ;  hence  the  areas  of  main  steam-  and 
return-pipes  should  be  6  times  greater  than  those  given  by  the 
table  on  page  237. 

154.  Size  of  Boiler  Required. — From  the  preceding  state- 
ment and  by  reference  to  page  124  it  is  seen  that  one  square 
foot  of  heating  surface  in  hot-blast  heating  will  condense  from 
0.7  to  0.9  the  amount  of  steam  that  can  be  produced  by  one 
square   foot   of  heating  surface   in   the    boiler.     Hence   there 
should  be  from  0.7  to  0.9  as  much  area  of  heating  surface  in 
the  boiler  as  in  the  indirect   heater,  or  in  other  words  there 
should  be  one  boiler  horse-power  for  every   15   to   18  square 
feet  in  the  heater.     The  proportions  of  grate  surface,  chimney, 
etc.,  will  be  found  by  consulting  Article  74,  page  124. 

155.  Practical  Construction  of  the  Hot-blast  System  of 
Heating. — The  following  matter  regarding  the  construction  of 
hot-blast  heating   plants   has    been   kindly  furnished  for  this 
book  by  Mr.  F.  R.  Still  of  Detroit,  who  has  had  an  extensive 
engineering  experience  in  this  particular  kind  of  work  : 

*  See  Table  VIII,  temp,  at  70°  F. 


FORCED-BLAST  SYSTEMS.  293 

"Air  Required. — The  following  is  intended  to  give  the  basis 
of  calculation  for  different  parts  of  a  plant  of  the  so-called  hot- 
blast  system.  The  first  thing  to  consider  with  this  system 
usually  is  the  amount  of  air  to  be  delivered  and  warmed  per 
minute.  Experience  has  proved  that  the  delivery  of  an  amount 
of  air  into  a  building  or  apartment  equal  to  its  cubic  contents 
every  15  minutes,  will  warm  it  under  average  conditions  of  con- 
struction to  70  degrees  F.  when  the  outside  temperature  is  zero. 
This  amount  of  air  will  accomplish  like  results  in  some  buildings 
when  the  outside  temperature  is  10  or  even  20  degrees  below 
zero,  and  in  other  cases  this  amount  will  be  found  insufficient ; 
the  variation  being  due  to  construction,  glass  surface,  and  con- 
ditions which  have  been  previously  mentioned  on  page  58. 
In  some  classes  of  buildings,  for  instance,  churches,  school- 
houses,  theatres,  and  hospitals,  a  change  of  air  may  be  required 
every  10  minutes. 

Amount  of  Heating  Surface.  —  Having  determined  the 
amount  of  air  required,  the  next  consideration  is  the  amount 
of  heating  surface  to  be  used  in  the  indirect  heater.  This  can 
be  treated  better  by  taking  a  specific  example,  for  instance, 
suppose  that  20,000  cubic  feet  of  air  to  be  delivered  into  the 
building  every  minute  (1,200,000  cubic  feet  per  hour)  at  a 
temperature  of  120  degrees,  when  air  outside  is  zero,  that  the 
steam-pressure  on  the  coils  or  heating  surface  is  10  pounds  per 
square  inch,  and  that  the  temperature  of  the  water  of  condensa- 
tion is  213  degrees.  In  one  pound  of  steam  at  a  pressure  of 
10  pounds  above  the  atmosphere  there  is  1186.5  units  of  heat, 
while  in  one  pound  of  water  of  condensation  there  is  213 
units,  leaving  973.5  units,  which  is  given  off  by  the  heating 
surface.  By  consulting  Table  VIII  it  will  be  seen  that  at  tem- 
perature of  70°  F.  one  heat-unit  will  warm  56  cubic  feet  of  air 
one  degree,  and  hence  to  heat  one  cubic  foot  120  degrees 
will  require  2.15  heat-units:  each  pound  of  steam  gives 
off  973.5  heat-units  and  will  heat  452  cubic  feet  of  air  from 
zero  to  1 20  degree.  To  heat  1,200,000  cubic  feet  of  air  to  120 
degrees  will  require  2660  pounds  of  steam.  The  indirect 
heater  provided  with  blower  will  condense  under  average 
conditions  2  pounds  of  water  per  square  foot  of  surface 
per  hour,  and  hence  we  should  require  as  many  square  feet  of 


2Q4  HEATING   AND.    VENTILATING   BUILDINGS. 

surface  as  the  quotient  of  2660  divided  by  2,  or  1330  square 
feet.* 

Size  of  Boiler. — To  find  the  size  of  boiler  needed,  divide  the 
total  steam  required  per  hour,  in  the  example  2660,  by  that  re- 
quired for  one  boiler  horse-power;  this,  when  water  of  conden- 
sation is  all  returned  to  boiler,  is  34.5  pounds  (see  page  122), 
and  we  obtain  77  horse-power.  This  computation  gives  a 
larger  boiler  than  would  generally  be  installed  for  work  of  this 
magnitude.  The  rated  horse-power  of  a  boiler  is  capable  of 
considerable  increase  in  times  of  necessity  and  for  short  periods. 
It  can  hardly  be  considered  good  practice  to  overwork  a 
boiler,  but  as  extremely  severe  weather  is  usually  of  very 
short  duration  and  the  balance  of  the  season  mild,  there  is 
good  reason,  on  the  score  of  economy  in  first  cost,  for  this 
practice.  The  boiler  is  usually  rated  on  the  supposition  that 
it  will  need  to  supply  1.5  pounds  of  steam  for  each  square  foot 
of  surface  in  the  radiator  per  hour,  in  which  case  23  square 
feet  of  surface  would  be  supplied  by  one  boiler  horse-power. 
This  estimate  would  require  the  normal  rating  of  the  boiler 
to  be  developed  during  the  average  stress  of  weather;  this 
method  would  require  a  boiler  of  about  60  horse-power  for  the 
plant  considered  in  the  example.  Such  a  method  of  pro- 
portioning has  proved  quite  satisfactory  in  actual  practice, 
although  greater  economy  could,  no  doubt,  be  obtained  by 
using  a  larger  boiler. 

Size  of  Blower. — We  are  next  to  determine  the  size  of 
blower  required,  which  in  some  respects  is  the  most  difficult 
part  relating  to  the  design,  as  much  depends  on  the  location  of 
the  fan  and  the  various  uses  to  which  the  building  is  to  be  put. 
Noise  is  an  objection  in  any  kind  of  a  building  except  perhaps 
one  devoted  to  manufacturing.  A  good  basis  from  which  to 
determine  the  velocity  of  the  air  is  that  relating  to  the  highest 
speed  at  which  the  blower  can  be  driven  without  making  a 
serious  noise.  This  limit  of  speed  is  found  to  be  about  250 
revolutions  per  minute,  but  except  in  rare  cases  the  blower 
should  run  at  from  180  to  200  revolutions.  We  do  not  advo- 


*  Some  manufacturers  claim   5  pounds  of  condensation  at  zero  weather  ; 
highest  results  obtained  by  Mr.  Still  were  3.5  pounds. 


FORCED-BLAST  SYSTEMS.  295 

ircate  a  linear  velocity  of  the  air  through  the  discharge  of  a 
blower  in  excess  of  2400  feet  per  minute,  and  it  will  be  found 
to  give  better  economy  and  more  satisfactory  results  if  the 
velocity  does  not  exceed  1500  or  1800  feet ;  though  in  some  in- 
stances this  low  velocity  may  require  a  large  and  unsightly  fan. 

Assuming,  as  in  the  example,  that  the  blower  is  to  deliver 
20,000  cubic  feet  of  air  per  minute  at  a  velocity  not  exceeding 
2000  feet  per  minute,  the  following  considerations  must  receive 
attention  :  A  blower  standing  in  an  open  room  and  having  a 
free  inlet  and  outlet  will  discharge  air  at  a  velocity  nearly  10 
[per  cent  greater  than  the  peripheral  velocity  of  the  fan-blades, 
but  attach  this  blower  to  a  bank  of  heating  coils  and  a  system  of 
conduits  and  the  resistance  due  to  friction  becomes  so  great  that 
it  reduces  this  velocity  nearly  50  per  cent.  To  allow  for  this  loss 
and  retain  a  factor  of  safety  it  is  customary  to  call  the  periph- 
|eral  velocity  of  the  fan-blades  equal  to  the  linear  velocity  of 
the  air,  and  to  figure  on  the  efficiency  of  delivery  in  actual 
work  as  50  per  cent  of  this  amount.  On  this  basis  a  velocity 
of  2000  feet  through  the  discharge  of  the  blower  will  be  main- 
tained when  the  peripheral  velocity  of  the  fan  is  about  4000 
feet.  Having  determined  that  the  blower  is  not  to  run  over 
200  revolutions  per  minute,  it  will  be  necessary  to  have  fan- 
wheels  for  this  peripheral  speed  6.4  feet  in  diameter.  A  fan 
6  feet  in  diameter  running  200  revolutions  has  a  peripheral 
velocity  of  3770  feet  per  minute,  so  that  the  air  delivered,  with 
50  per  cent  allowance  for  friction  will  move  at  the  rate  of  85 
feet  per  minute.  A  blower  of  any  standard  make,  having  a 
wheel  6  feet  in  diameter,  would  be  provided  with  a  discharge- 
opening  at  least  11.5  square  feet  in  area.  The  product  of  this 
area  by  1885  gives  a  discharge  of  21,677  cubic  feet  per  minute, 
which  is  slightly  more  than  is  required  in  the  example  con- 
sidered. 

Power  Required. — The  next  consideration  is  the  amount  of 
power  required  to  drive  the  blower,  regarding  which  we  will  say 
that  we  know  of  no  formula  which  has  sufficient  elasticity 
to  apply  alike  to  large  and  small  blowers  at  high  and  low 
speeds.  The  following  tables  give  the  results  of  the  actual 
power,  as  obtained  by  testing,  required  to  operate  various  sizes 
of  Smith  fans  when  delivering  a  specified  amount  of  air: 


296 


HEATING  AND    VENTILATING  BUILDINGS. 


TABLE   OF   CAPACITY   AND    POWER    FOR   STEEL-PLATE 
BLOWERS   OF   VARIOUS   SIZES. 


Size. 

o  . 

%  Oz.  Pres. 

Y%  Oz.  Pres.   %  Oz  Pres. 

i  Oz.  Pres. 

2  Oz.  Pres. 

In. 

£  J3 

£| 

£.5 

£•- 

£•- 

£•-' 

s  *^. 

> 

cu 

> 

pu 

> 

.  ^ 

P- 

£» 

•  ^ 

OH 

£> 

S 

A 

Q 

£ 

ul 

re 

K 

3« 

uS. 

3& 

E 

04 

3  i 

u  & 

K 

C* 

3  <U 

ua 

I 

70 

42 

214 

10336 

•3 

312 

14628 

1  3 

377 

17928 

1.6 

428 

20700 

3-7 

607 

29352 

10.5 

80 

48 

188 

12584 

•5 

20=; 

17809 

1.6 

325 

21827 

2.4 

367 

25202 

4-5 

35736:12.8 

90 

16150 

•  7 

236 

22856 

2.0 

2.6 

289 
260 

28012 

4  8 

333 

32343 

5-7 

472 

45860  16.4 

58850!"'   T 

no 

66 

24548 

i  .1 

34741 

236 

42579 

S-7 

273 

49162 

8.8 

387 

697II 

25.0 

120 

72 

125 

30165 

1.3 

177 

42678 

3-8 

217 

52304 

7.0 

250 

60392 

10.7 

3S4 

85634  30.7 

140 

84 

107 

40465 

1.8 

152 

57268 

5-1 

186 

70188 

9-4 

214 

81040 

14  4 

304 

t'4913 

4*-3 

160 

96 

94 

51344 

2-3 

*33 

72264 

6.4 

163 

89057  11.5 

102807 

18.3 

260 

145806 

52-4 

TABLE   OF   DIMENSIONS.* 
FAN  WITH  STEEL- PL  ATE  HOUSING. 


£' 

Size  of 

1 

1 

3 

J3 
<S) 

Inlet. 

Outlet. 

Engine 
Cylinder 
In. 

Weights. 

«4-l 

Size 

G 

— 

o 

O 

of 

1 

fc 

<u 

« 

Pulley. 

u 

• 

. 

*o 

i$ 

<L> 

I 

rt 

V 

i 

« 

In. 

iamet 

c  £ 

Scr 
Cv) 

Size. 
In. 

C  ^ 

~u 

jU 

be 

c 

S          Fan 
|    1     Only. 

Single 
Engine. 

Double 
Engine. 

c7J 

Q 

Q 

Q 

< 

< 

t/J 

Q 

70 

42 

2T^      14  x   8j>*j 

26 

530 

24        X24 

576 

4x4 

3X3 

1000 

1290 

1330 

80 

48 

2T6S      i6x   8>^ 

3° 

706 

26^x26^ 

702 

4x4 

3X3 

1300 

1590 

1630 

9° 

54 

2T5g          1  8  X  10  Vt 

34 

907 

30      x3o 

900 

5X5;4X4 

1650 

2150 

2190 

100 

60 

2^ 

20  X  10^ 

38 

"34 

34      x  34  ' 

1156 

6x6 

5X5 

2000 

2640 

2850 

no 

66 

2-^j 

22  X  10^ 

42 

1385 

37      X37 

1369 

6x6 

5X5 

2500 

3  HO 

3350 

120 

72 

2ll 

24XI2J4 

46 

1661 

41      x4i 

1681 

7x7 

6x6 

3000 

3870 

4300 

140 

84 

3^S 

28  x  12^6 

53 

2206 

47^x47^ 

2256 

.... 

7x7 

4OOO 

5600 

5700 

160 

96 

3T^      32  x  12^ 

60  12827 

53^X53^ 

2862 

7x7 

5200 

6800 

6900 

*  Catalogue  American  Blower  Co. 

Capacity  of  Blower. — The  120-inch  fan  has  a  wheel  6  feet 
in  diameter,  as  shown  by  the  table  of  dimensions.  By  consult- 
ing the  table  of  powers  it  will  be  seen  that  this  fan,  running 
with  a  speed  of  200  revolutions  per  minute,  requires  less  than 
7  horse-power  to  drive  the  blower.  The  capacity,  as  given 
under  the  same  head,  is  that  for  a  fan  working  with  free  inlet 
and  outlet,  and,  as  before  remarked,  is  about  10  per  cent 
greater  than  the  capacity  when  delivering  into  conduits.  To 
totally  close  off  either  inlet  or  discharge  of  the  blower  causes 
the  air  to  move  around  with  the  fan  ;  this  removes  so  much  load 


FORCED-BLAST  SYSTEMS. 

from  the  engine  that  unless  it, is  provided  with  an  excellent 
governor  it  will  speed  up  to  a  very  great  rate  and  may  run 
away.  This  fact  that  an  increase  of  resistance  diminishes  the 
power  required  at  different  speeds  is  not  considered  in  the 
tables  given ;  consequently  these  powers  are  somewhat  in  ex- 
cess of  those  actually  required.  The  excess  of  power  would 
depend  upon  friction  and  other  resistances ;  consequently  no 
allowan.ce  can  be  made  which  would  be  accurate  for  all  con- 
ditions. 

Dimensions  of  Horizontal  Conduits. — We  now  come  to  the 
question  regarding  dimensions  of  horizontal  conduits  that  con- 
vey the  air  from  the  blower  to  various  parts  of  the  building. 
There  is  a  great  difference  of  opinion  as  to  the  proper  velocity 
of  the  air  through  such  conduits,  and  circumstances  have  a 
great  deal  to  do  with  this  question.  In  my  opinion  the  easier 
you  make  it  for  the  air  to  travel  the  more  successful  will  be 
the  plant.  In  no  plants,  in  public-buildings,  do  we  advocate  a 
velocity  of  air  that  exceeds  15  feet  per  second,  or  900  feet  per 
minute ;  600  feet,  or  even  400  feet,  is  better,  although  in  an 
extensive  plant  the  conduits  might  be  so  large  as  to  be  un- 
sightly and  interfere  with  the  convenience  of  the  building. 
Vertical  flues  in  the  walls  leading  to  the  various  apartments 
should  be  so  large  that  the  velocity  of  the  air  will  not  exceed 
10  feet  per  second,  or  600  feet  per  minute. 

Maximum  Velocity  of  Air. — From  an  economical  and  efficient 
standpoint  air  should  never  enter  a  room  through  a  register, 
screen,  or  grille  at  a  velocity  exceeding  400  feet  per  minute 
(6.6  feet  per  second).  A  greater  velocity  is  liable  to  create 
such  a  rapid  movement  of  the  air  as  will  stir  up  the  dust  in  the 
room  and  create  serious  throat  affections.  Again,  air  coming 
in  contact  with  the  screen  at  a  very  high  velocity  will  cause  a 
low  whirr  or  whistle  often  proving  very  annoying.  Better 
ventilation,  or  perhaps  we  should  say  better  circulation  of  the 
air,  takes  place  when  introduced  at  a  moderate  velocity  than  at 
a  high  velocity,  because  in  that  case  the  air  enters  gently  and 
is  distributed  by  gravitation,  due  to  the  cooling  of  the  air  in 
contact  with  cold  walls,  and  the  whole  body  of  air  is  thus  kept 
in  slight  motion  and  the  entering  air  is  more  evenly  distributed. 
If  the  air  is  forced  in  at  high  velocity,  it  creates  swift  currents 


298  HEATING   AND    VENTILATING   BUILDINGS. 

and  counter-currents,  which  will  completely  prevent  the 
equitable  distribution  of  the  fresh  air. 

Introduction  of  Air. — My  method  of  introducing  air  into  a 
room  is  from  a  register  about  8  feet  above  the  floor,  connected 
with  a  flue  located  in  an  inside  wall,  and  discharging  the  cur- 
rent of  air  in  the  direction  of  an  outside  wall.  The  vent  regis- 
ter should  be  located  in  the  same  wall  as  the  fresh-air  register, 
but  at  the  opposite  side  and  in  the  warmest  corner  of  the 
room.* 

General  Remarks. — Architects  very  often  combat  such  ar- 
rangements on  the  ground  of  interfering  with  their  plans  or  of 
taking  up  too  much  room,  and  very  often  seriously  object  to 
making  even  the  slightest  alteration.  This  often  leads  to  sorry 
arrangements  for  heating  and  ventilating  plants,  which  will 
probably  always  continue  so  long  as  competiting  manufacturers 
design  those  to  be  installed  in  certain  buildings. 

It  may  be  said  generally  that  while  the  method  of  design- 
ing, followed  by  different  manufacturers,  may  be  essentially 
different  from  that  given  here,  yet  the  experience  of  the  writer 
has  shown  that  the  quantities,  as  computed  by  various  manu- 
facturers when1  submitting  plans  in  competition  for  the  same 
building,  are  essentially  the  same  as  those  stated  here. 

156.  Systems  of  Ventilation  without  Heating.— Where 
large  quantities  of  air  are  required,  especially  in  seasons  when 
heat  is  not  needed,  systems  of  ventilation  may  be  constructed 
which  are  independent  from  the  systems  of  heating.  The  cir- 
culation of  the  air  through  the  building  may  be  produced  either 
by  exhausting  or  rarefying  the  air  in  the  discharge-ducts,  or  by 
delivering  fresh  air  to  the  rooms  under  pressure,  as  described 
for  hot-blast  heating. 

The  air  may  be  rarefied  in  the  discharge-flue  by  heating 
either  with  steam  or  hot-water  radiators,  with  an  open  fire- 
place or  a  stove.  When  circulation  is  produced  by  heat,  the 
amount  of  air  moved  will  depend  upon  the  height  of  the  chim- 
ney or  discharge-duct  and  its  temperature,  and  will  be  essen- 
tially as  that  given  in  the  table  on  page  45.  The  air  may  also 

*  The  above  opinion  gives  the  practice  of  Mr.  Still,  and  is  different  from 
lhat  of  many  engineers.     See  a  full  discussion  of  the  matter  on  pages  44  to  49. 


FORCED-BLAST  SYSTEMS.  299 

be  exhausted  from  the  building  by  induction,  for  which  may 
be  used  a  jet  of  steam,  water,  or  compressed  air  which  is  de 
livered  from  a  nozzle  into  a  convergent  pipe  of  somewhat  larger 
diameter  and  with  both  ends  open.    A  very  strong  draft  can  be 
;  produced  in  this  way,  although  at  the  expense  of  more  energy 
than  that  required  to  operate  exhaust  fans  or  blowers.     The 
;  air  may  also  be  exhausted  by  means  of  a  fan  located  in  the 
main  flue.     In  case  any  of  these  means  for  producing  drafts 
;by  exhausting  or  rarefying  the   air  in   the  discharge-ducts  is 
employed,  every  precaution  that  has  been  mentioned  in  regard 
to  chimney-tops  (page   162)  should  be  observed,  otherwise  a 
considerable  portion  of  the   force  may  be  required  to   over- 
come adverse  wind  currents. 

The  general  remarks  regarding  hot-blast  heating-systems 
and  also  the  tables  of  dimensions  apply  equally  well  to  this  case. 
The  tables  on  page  52  will  be  useful  in  proportioning  areas  of 
flues  and  registers  for  the  discharge  of  a  given  amount  of  air  ;  as 
an  allowance  for  friction  add  one  inch  to  each  lineal  dimension. 

The  blower  system  of  ventilation  has  been  fully  described 
in  connection  with  the  hot-blast  system  of  heating,  and  tables 
of  capacities  of  various  fans  given  which  are  applicable  to  this 
case.  In  this  system  as  well  as  in  the  hot-blast  system  of 
heating  especial  care  should  be  taken  that  the  resistances  in 
pipes  and  flues  are  as  small  as  can  be  made,  that  bends  are 
made  with  a  long  radius,  and  that  the  reduction  in  size  in  pass- 
ing from  one  pipe  to  another  is  as  gradual  as  possible. 

157.  Heating  with  Refrigerating  Machines. — The  refrig- 
erating machine  is  virtually  a  pump  which  removes  heat  from 
a  body  at  one  temperature  and  discharges  it  at  a  higher  tem- 
perature. Reckoned  on  the  basis  of  heat  transmitted,  it  is  a 
very  efficient  machine,  as  it  may  move  from  a  lower  to  a  higher 
temperature  10  to  20  times  as  much  heat  as  the  mechanical 
equivalent  of  the  work  performed ;  in  all  respects  this  machine 
is  the  converse  of  the  steam-engine.  By  utilizing  the  heat 
which  is  discharged  from  a  machine  of  this  character  in  warm- 
ing a  building,  and  also  that  in  the  exhaust  steam  from  the 
engine  working  the  compressor  pump,  there  is  a  possible  effi- 
ciency many  times  greater  than  that  which  can  be  obtained 
by  burning  the  coal  directly. 


300  HEATING   AND    VENTILATING   BUILDINGS. 

The  practical  arrangement  of  such  a  machine,  if  using  air 
as  the  working  fluid,  would  be  such  as  to  draw  in  air  from  the 
outside,  compress  it  to  such  a  point  that  its  temperature  would 
be  very  high,  pass  it  through  circulating  pipes  and  radiating 
surfaces  when  still  under  pressure,  and  discharge  into  a  cham- 
ber from  which  the  pressure  has  been  removed,  or  in  the  out- 
side air  after  being  cooled.  If  the  exhaust  steam  could  be 
used  for  heating,  such  a  system  would  be  very  economical, 
although  it  would  be  costly  and  take  up  considerable  room. 
An  ammonia  refrigerating  machine  might  be  used,  in  which  case 
the  heat  in  the  compressed  ammonia  could  be  removed  by 
water,  which  would  thus  become  heated  and  could  be  circulated 
for  the  purpose  of  warming.  The  scheme  of  using  the  re- 
versed heat-engine  or  refrigerating  machine  as  a  warming 
machine  was  pointed  out  first  by  Lord  Kelvin  in  1852,*  and 
although  it  presents  great  advantages  economically,  the  writer 
has  no  data  showing  that  it  has  ever  been  put  to  practical  use. 

158.  Cooling  of  Rooms. — The  converse  operation  of  cool- 
ing rooms,  although  at  the  present  not  undertaken  except  in 
the  case  of  cold-storage  plants  and  warehouses,  bids  fair  to  be 
at  some  time  an  industry  of  considerable  importance.  Rooms 
may  be  artificially  cooled  by  a  system  constructed  similar  to 
that  described  for  hot-blast  heating.  The  coils  or  radiating 
surface,  however,  would  need  to  be  replaced  by  ice  or  con- 
structed in  such  a  manner  that  ammonia  or  some  liquid  at  a 
very  low  temperature  could  be  circulated.  Over  these  the  air 
could  be  driven,  its  heat  would  be  absorbed,  and  it  could  be 
reduced  in  temperature  to  any  point  desired.  In  lowering  the 
temperature  of  the  air,  a  considerable  amount  of  moisture 
might  be  precipitated,  and  some  means  should  be  provided 
for  artificially  removing  it  without  heating,  otherwise  the  rooms 
would  be  made  damp.  It  may  be  remarked  that  ordinary 
pipe-fittings  cannot  be  used  with  safety  for  ammonia  circula- ; 
tion,  and  that  special  fittings  are  manufactured  for  this  purpose. 

*  Proc.  of  the  Phil.  Soc.  of  Glasgow,  Vol.  Ill,  p.  269. 


CHAPTER   XIV. 
HEATING  WITH  ELECTRICITY. 

159.  Equivalents  of   Electrical  and   Heat    Energy.— 

Electrical  energy  can  all  be  transformed  into  heat,  and  as  there 
are  certain  advantages  pertaining  to  its  ready  distribution,  it 
s  likely  to  come  into  more  and   more  extended  use  for  heat- 
ng,  especially  where  the  cost  is  not  of  prime  importance.    The 
value  of  mechanical   and  electrical  units  has    been    given   on 
>age  5,  from  which  it  will  be  seen  that  one  watt  for  one  hour, 
vhich  is  the  ordinary  commercial  unit  for  electricity,  is  equal 
o  3.41  heat-units  ;  for  one  minute  it  is  1/60  and  for  one,  second 
t  is  1/3600  this  amount.     Electricity  is  usually  sold  on  the 
)asis  of  IOOO*  watt-hours  as  a  unit  of  measurement,  the  watts 
>eing  the  product  obtained  by  multiplying  the  amount  of  cur- 
rent estimated  in  amperes  by  the  pressure  or  intensity  esti- 
mated in  volts ;  on  this  basis  1000  watt-hours  is  the  equivalent 
of  3410  heat-units.     We  have  considered  in  Chapter  III  the 
amount  of  heat  required  per  hour  for  the  purpose  of  warming. 
This  amount  divided  by  3410  will  give  the  equivalent  value  in 
dlowatt-hours  which  would  need  to  be  supplied  for  the  re- 
quired amount  of  heat. 

160.  Expense  of  Heating  by  Electricity. — The  expense 
of  electric  heating  must  in  every  case  be  very  great,  unless  the 
electricity  can  be  supplied  at  an  exceedingly  low  price.     Much 
data  exists  regarding  the  cost  of  electrical  energy  when  it  is 
obtained    from    steam-power.     Estimated  f   on   the    basis   of 

*  One  thousand  watts  is  called  a  kilowatt. 

\  The  mechanical  energy  in  one  horse-power  is  equivalent  to  0.707  B.  T.  U. 
per  second  or  2545  per  hour.  One  pound  of  pure  carbon  will  give  oft  14,500 
heat-units  by  combustion,  which  if  all  utilized  would  produce  5.7  horse-power 

301 


302  HEATING   AND    VENTILATING   BUILDINGS. 

present  practice,  the  average  transformation  into  electricity, 
does  not  account  for  more  than  4  per  cent  of  the  energy  in 
the  fuel  which  is  burned  in  the  furnace  ;  although  under  best 
conditions  15  per  cent  has  been  realized,  it  would  not  be  safe 
to  assume  that  in  commercial  enterprises  more  than  5  per 
cent  could  be  transformed  into  electrical  energy.  In  transmit- 
ting this  to  a  point  where  it  could  be  applied  losses  will  take 
place  amounting  to  from  10  to  20  per  cent,  so  that  the 
amount  of  electrical  energy  which  can  be  usefully  applied 
for  heating  would  probably  not  average  over  4  per  cent  of 
that  in  the  fuel.  In  heating  with  steam  or  hot  water  or  hot 
air  the  average  amount  utilized  will  probably  be  about  60  per 
cent,  so  that  the  expense  of  electrical  heating  is  approxi- 
mately as  much  greater  than  that  of  heating  with  coal  as  60 
is  greater  than  4,  or  about  15  times.  If  the  electrical  current 
can  be  furnished  by  water-power  which  otherwise  would  not 
be  usefully  applied,  these  figures  can  be  very  much  reduced. 
The  above  figures  are  made  on  the  basis  of.  fuel  cost  of  the 
electrical  current,  and  do  not  provide  for  operating,  profit, 
interest,  etc.,  which  aggregate  many  times  that  of  the  fuel. 
With  coal  at  $3.30  per  ton  this  cost  on  above  basis  is  about  .97 
cent  per  thousand  watt-hours.  The  lowest  commercial  price 
quoted,  known  to  the  writer,  for  the  electric  current  was  3 
cents  ;  per  thousand  watt-hours  the  ordinary  price  for  lighting 
current  varies  from  10  to  20  cents.  It  may  be  said  that  for 
lighting  purposes  10  cents  per  thousand  watt-hours  is  con- 
sidered approximately  the  equivalent  of  gas  at  $1.25  per  thou- 
sand cubic  feet. 

It  may  be  a  matter  of  some  interest  to  consider  the  method 
of  computation  employed  for  some  of  these  quantities.  The 
ordinary  steam-engine  requires  about  4  pounds  of  coal  for  each 
horse-power  developed ;  on  account  of  friction  and  other  losses 
about  1.5  horse-power  are  required  per  kilowatt,  or  in  other 

for  one  hour,  in  which  case  one  horse  power  could  be  produced  by  the  combus- 
tion of  0.175  Ib.  of  carbon.  The  best  authenticated  actual  performance  is  one 
horse-power  for  1.2  Ib.,  corresponding  to  14.6  per  cent  efficiency.  The  usual 
consumption  is  not  less  than  4  to  6  pounds  per  indicated  horse-power,  or  from 
3  to  5  times  the  above.  A  kilowatt  is  very  nearly  \\  horse-power,  but  because 
of  friction  and  other  losses  requires  an  engine  of  1.5  indicated  horse-power. 


HEATING    WITH  ELECTRICITY. 


303 


words  6  pounds  of  coal  are  required  for  each  thousand  watts 
of  electrical  energy.  In  the  very  best  plants  where  the  output 
is  large  and  steady  this  amount  is  frequently  reduced  20  to  30 
per  cent  from  the  above  figures  in  cost.  The  cost  of  6  pounds 
of  coal  at  $3.33  per  ton  is  one  cent.  To  this  we  must  add 
transmission  loss  about  10  per  cent,  attendance  and  interest  20 
per  cent,  making  the  actual  cost  per  kilowatt  1.3  cents  per 
hour.  As  one  pound  of  coal  represents  from  13,000  to  15,000 
heat-units,  depending  upon  its  quality,  and  one  kilowatt-hour 
is  equivalent  to  3415  heat-units,  if  there  were  no  loss  whatever 
tin  connection  with  transformation  of  heat  into  electricity,  one 
pound  of  coal  should  produce  4  to  5  kilowatts  per  hour  of 
electrical  energy.  This  discussion  is  sufficient  to  show  that  at 
[cost  prices  electrical  heating  obtained  from  coal  will  amount 
under  ordinary  conditions  to  15  to  20  times  that  of  heating 
:with  steam  or  hot  water,  and  at  commercial  prices  which  are 
likely  to  be  charged  for  current  its  cost  will  be  from  2  to  10 
times  this  amount. 

The  following  table  gives  the  cost  of  a  given  amount  of  heat, 

COST   OF   HEAT   OBTAINED    FROM    ELECTRICITY. 


Cost  per  kilowatt  hour,  cents. 

Heat- 

units. 

i 

2           |         3 

4 

5 

6 

7 

8 

9 

10 

B.  T.  U. 

1 

Cost  of  heat  obtained,  cents. 

IO.OOO 

2.93 

S.86 

8.78 

11.71 

14.64 

17-57 

20.50 

23.42 

26.35 

29.28 

20.000 

5.85 

11.68 

17.57 

23.42 

29.28 

35.13 

40.99 

46.84 

52.70 

58.56 

30,000 

8.78 

17-57 

26.35 

35-M 

43.92 

52.70 

61.49 

70.28 

79.06 

87-84 

4O,OOO 

11.71 

22.42 

35-14 

46.84 

58.56 

70.28 

81.98 

93-68 

105.40 

117.12 

50,000 

14.64 

29.28 

43-92 

58.56 

73-20 

87.84 

102.48 

117.12 

131.86 

146.40 

6o,OOO 

17-57 

35-14 

52-70 

70.28 

87.84 

105.40 

122.98 

140.56 

158.12 

175.68 

7O,OOO 

20.50 

40.99 

61.49 

81.98 

102.48 

122.98 

M3.47 

163.96 

184.46 

204.96 

So,ooo      23.42 

46.84 

70.28 

93-68 

117.12 

140-56 

163.97 

187.36 

210.80 

234-24 

qO,000      !26.35 

52.70 

79.06 

105.42 

131-76 

158.  10 

184.46 

210.84 

237.17 

263    52 

100,000 

29.28 

58.56 

87-84 

117.12 

146.40 

175.68 

204.96 

234.24 

263.52 

292  .  8O 

i 

NOTE. — 10,000  heat-units  is  equal  to  two  thirds  the  heat  contained  in  one 
pound  of  the  best  coal,  and  is  very  near  the  average  amount  that  can  be  realized 
per  pound  in  steam  or  hot-water  heating,  hence  the  table  can  also  be  considered 
as  showing  the  relative  price  of  electricity  and  coal  for  the  same  amount  of 
heating.  For  instance,  if  5  cents  per  kilowatt  hour  is  charged  for  electric 
current,  the  expense  would  be  the  same  as  that  of  good  coal  at  14.64  cents  per 
pound,  which  is  at  rate  of  $392.80  per  ton. 


304  HEATING   AND    VENTILATING   BUILDINGS, 

if  obtained  from  the  electric  current,  furnished  at  different] 
prices.  Thus  30,000  heat-units  if  obtained  from  electric  current! 
furnished  at  8  cents  per  kilowatt  hour  would  cost  70.28  cents 
per  hour.  The  amount  of  heat  needed  for  various  buildings 
can  be  determined  by  methods  stated  in  Chap.  III. 

There  are  some  conditions  where  the  cost  is  not  of  moment^ 
and  where  other  advantages  are  such  as  to  make  its  use  desir- 
able. In  such  cases  electricity  will  be  extensively  used  for] 
heating. 

For  the  purposes  of  cooking  it  will  be  found  in  many  cases 
that  electrical  heat,  despite  its  great  first  cost,  is  more  econom-' 
ical  than  that  obtained  directly  from  coal.  This  is  due  to  the 
fact  that  of  the  total  amount  of  heat,  which  is  given  off  fromj 
the  fuel  burned  in  a  cook  stove  very  little,  perhaps  less  than] 
one  per  cent,  is  applied  usefully  in  cooking:  the  principal  pard 
is  radiated  into  the  room  and  diffused,  being  of  no  use  what- 
ever for  cooking,  while  the  heat  from  the  electric  current  can 
be  utilized  with  scarcely  any  loss. 

161.  Formulae  and  General  Considerations.  —  The  fol- 
lowing formulae  express  the  fundamental  conditions  relating 
to  the  transformation  of  the  electric  current  into  heat  : 


W=CE=C*K.   /   .    ,    ....    (2) 


.     -     (3)  H=o.2iC*R.     .     .     .     ...     .     .     (4) 

>fci  =  .00000009  5  C"*R.     (5)          hi  =  3.415  W  ~  3.41  5  C8A'  =  34I5CZT.     (6 

In  which  the  symbols  represent  the  following  quantities:  E,  electro 
motive  force  in  volts  ;  C,  intensity  of  current  in  amperes  ;  R,  resistanc 
of  conductor  in  ohms  ;  /,  the  length  in  metres  ;  w,  the  area  of  cross-sec 
tion  in  square  centimetres;  k,  coefficient  of  specific  resistance;  W,  kilo 
watts  ;  H,  the  heat  in  minor  calories,  and  h\  in  B.  T.  U.  per  second,  h 
the  heat  in  B.  T.  U.  per  hour. 

The  amount  of  heat  given  off  per  hour  is  given  in  equatioi 
(6),  and  is  seen  to  be  dependent  upon  both  the  resistance  an< 
the  current,  and  apparently  would  be  increased  by  increase  ii 
either  of  these  quantities.  The  effect,  however,  of  increasing 
the  resistance  as  seen  by  equation  (i)  will  be  to  reduce  th 
amount  of  current  flowing,  so  that  the  total  heat  suppliec 


HEATING    WITH  ELECTRICITY.  305 

would  be  reduced  by  this  change.  On  the  other  hand,  if  there 
were  no  resistance  no  heat  would  be  given  off,  for  to  make 
R  =  o  in  equation  (6)  would  result  in  making  //2  =  o.  From 
these  considerations  it  is  seen  that  in  order  to  obtain  the 
maximum  amount  of  heat,  the  resistance  must  have  a  certain 
mean  value  dependent  upon  the  character  of  material  used  for 
'the  conductor  in  the  heater,  its  length  and  diameter. 

For  purposes  of  heating,  a  constant  electromotive  force  or 

voltage  is  maintained  in  the  main  wire  leading  to  the  heater. 

A  very  much  less  voltage  is  maintained  on  the  return  wire,  and 

[the  current  in  passing  through  the  heater  from  the  main  to  the 

[return  drops  in  voltage  or  pressure.     This  drop  provides  the 

energy  which  is  transformed  into  heat. 

The  principle  of  electric  heating  is  much  the  same  as  that 
involved  in  the  non-gravity  return  system  of  steam-heating. 
In  that  system  the  pressure  on  the  main  steam-pipes  is  essen- 
tially that  at  the  boiler,  that  on  the  return  is  much  less,  the 
reduction  of  pressure  occurring  in  the  passage  of  the  steam 
through  the  radiators ;  the  water  of  condensation  is  received 
into  a  tank  and  returned  to  the  boiler  by  a  steam-pump.  In  a 
system  of  electric  heating  the  main  wires  must  be  sufficiently 
large,  to  prevent  a  sensible  reduction  in  voltage  or  pressure 
between  the  dynamo  and  the  heater,  so  that  the  pressure  in 
them  shall  be  substantially  that  in  the  dynamo.  The  pressure 
or  voltage  in  the  main  return  wire  is  also  constant  but  very  low, 
and  the  dynamo  has  an  office  similar  to  that  of  the  steam- 
pump  in  the  system  described,  viz.,  that  of  raising  the  pressure 
of  the  return  current  up  to  that  in  the  main.  The  power 
which  drives  the  dynamo  can  be  considered  synonymous  with 
the  boiler  in  the  other  case.  All  the  current  which  passes  from 
the  main  to  the  return  current  must  flow  through  the  heater, 
and  in  so  doing  its  pressure  or  voltage  falls  from  that  of  the 
main  to  that  of  the  return. 

Thus  in  Fig.  215  a  dynamo  is  located  at  D,  from  which 
main  and  return  wires  are  run,  much  as  in  the  two-pipe  system 
of  heating,  and  these  are  so  proportioned  as  to  carry  the  re- 
quired current  without  sensible  drop  or  loss  of  pressure. 
Between  these  wires  are  placed  the  various  heaters  ;  these 
are  arranged  so  that  when  electric  connection  is  made,  they 


306 


HEATING   AND    VENTILATING   BUILDINGS. 


draw  current  from  the  main  and  discharge  into  the  return  wire. 
Connections  which  are  made  and  broken  by  switches  take  the 


FIG.  215. — DIAGRAM  OF  ELECTRIC  HEATING. 

place  of  valves  in  steam-heating,  no  current  flowing  when  the 

switches  are  open. 

The  heating  effect  is  proportional  to  the  current  flowing, 

and  this  in  turn  is  affected  by 
the  length,  cross-section,  and 
relative  resistance  of  the  ma- 
terial in  the  heater.  The  resist- 
ance is  generally  proportioned 
such  as  to  maintain  a  constant 
temperature  with  the  electro- 
motive force  available,  and  the 
amount  of  heat  is  regulated  by 
increasing  the  number  of  con- 
ductors in  the  heater. 

162.  Construction  of  Elec- 
trical Heaters.— Various  forms 
of  heaters  have  been  employed. 
Some  of  the  simplest  consist 

FIG.  2i6.-ELECTRic  HEATER  AT  THE  merely  of  coils  or  loops  of  iron 
VAUDEVILLE  THEATRE,  LONDON.      wjre  arranged   in   parallel    rows 

so  that  the  current  can  be  passed  through  as  many  wires  as 

are  needed  to  provide  the  heat  required.     In  other  forms  of 


HEATING    WITH  ELECTRICITY. 


these  heaters  the  heating  material  has  been  surrounded  with 
fire-clay,  enamel,  or  some  relatively  poor  conductor,  and  in 
other  cases  the  material  itself  has  been  such  as  to  give  consid- 
erable resistance  to  the  current.  It  is  generally  conceded  that 


__>-i J 


FIG.  217. — OFFICE  OR  HOUSE  HEATER. 


the  most  satisfactory  results  are  obtained  with  electrical  as  with 
other  heaters  by  regulating  the  resistance,  by  change  of  length 
and  cross-section  of  the  conductor,  to  such  an  extent  as  to  keep 
the  heating  coils  at  a  moderately  low  temperature.  Some  of 


308 


HEATING   AND    VENTILATING   BUILDINGS. 


the  various  forms  which  have  been  used  are  shown  in  the  cuts. 
Fig.  216  represents  a  portable  form  of  electrical  heater  used  in 
the  Vaudeville  Theatre,  London.  Fig.  217  shows  the  interior 
of  an  office  or  house  heater  made  by  the  Consolidated  Car 
Heating  Co.,  of  Albany.  The  electrical  heating  surface  is  made 
in  the  latter  by  a  coil  of  wire  wound  spirally  about  an  incom- 
bustible clay  core.  The  casing  is  like  that  for  an  ordinary 


UU 


FIG.  218. — CAR  HEATER  OF  CONSOLIDATED  Co. 


FIG.  2TQ. — AMERICAN  CAR  HEATER. 

stove,  and  is  built  so  that  air  will  draw  in  at  the  bottom  and 
pass  out  at  the  top.  * 

The  electrical  heaters  at  the  present  time  are  used  almost 
exclusively  in  heating  electrical  cars,  where  current  is  available 
and  room  is  of  considerable  value.  These  heaters  are  generally 
located  in  an  inconspicuous  place  beneath  the  seats,  their  gen- 
eral form  being  shown  in  Figs.  218  and  219. 


HEATING    WITH  ELECTRICITY.  509 

163.  Connections  for  Electrical  Heaters. — The  method  of 
wiring  for  electrical  heaters  must  be  essentially  the  same  as  for 
lights  which  require  the  same  amount  of  current.  The  details 
of  this  work  pertain  rather  to  the  province  of  the  electrician 
than  to  that  of  the  steam-fitter  or  mechanic  usually  employed 
for  installing  heating  apparatus.  These  wires  must  be  run  in 
accordance  with  the  underwriters'  specifications,  so  as  not, 
under  any  conditions,  to  endanger  the  safety  of  the  building 
from  fire. 


CHAPTER  XV. 

TEMPERATURE   REGULATORS. 

164.  General  Remarks.— A  temperature  regulator  is  an 
automatic  device  which  will  open  or  close,  as  required  to  pro- 
duce a  uniform  temperature,  the  valves  which  control  the 
supply  of  heat  to  the  various  rooms.  Although  these  regula- 
tors are  often  constructed  so  as  to  operate  the  dampers  of  the 
heater,  they  differ  from  damper-regulators  for  steam-boilers, 
as  described  in  Article  91,  by  the  fact  that  the  latter  are  un- 
affected by  the  temperature  of  the  surrounding  air*  although 
acting  to  maintain  a  uniform  pressure  and  temperature  within 
the  boiler,  while  the  former  are  put  in  operation  by  changes  of 
temperature  in  the  rooms  heated. 

The  temperature  regulator,  in  general,  consists  of  three 
parts,  as  follows :  First,  a  thermostat  which  is  so  constructed 
that  some  of  its  parts  will  move  because  of  change  of  tempera- 
ture in  the  surrounding  ,air,  the  motion  so  produced  being  used 
either  directly  or  indirectly  to  open  dampers  or  valves,  and  thus 
to  control  the  supply  of  heat.  Second,  means  of  transmitting 
and  often  of  multiplying  the  slight  motion  of  the  parts  of  the 
thermostat  produced  by  change  of  temperature  in  the  room,  to 
the  valves  or  dampers  controlling  the  supply  of  heat.  Third, 
a  motor  or  mechanism  for  opening  the  valves  or  dampers, 
which  may  or  may  not  be  independent  from  the  thermostat. 

In  some  systems  the  thermostat  is  directly  connected  to 
the  valves  or  dampers,  and  no  independent  motor  or  mechanism 
is  employed ;  in  this  case  the  power  which  is  used  to  open  or 
close  the  valves  regulating  the  heat-supply  is  generated  within 
the  thermostat,  and  is  obtained  either  from  the  expansion  or 
contraction  of  metallic  bodies,  or  by  the  change  in  pressure 

310 


TEMPERATURE   REGULATORS.  311 

caused  by  the  vaporizing  of  some  liquid  which  boils  at  a  low 
temperature.  The  force  generated  by  slight  changes  in  tem- 
perature is  comparatively  feeble,  and  the  motion  produced  is 
generally  very  slight,  so  that  when  no  auxiliary  motor  is  em- 
ployed it  is  necessary  to  have  the  regulating  valves  constructed 
so  as  to  move  very  easily  and  not  be  liable  to  stick  or  get  out  of 
order.  In  most  systems,  however,  a  motor  operated  by  clock- 
work, water,  or  compressed  air  is  employed,  and  the  thermostat 
is  required  simply  to  furnish  power  sufficient  to  start  or  stop 
this  motor.  The  limits  of  this  work  do  not  permit  an  extended 
historical  sketch  of  many  of  the  forms  which  have  been  tried. 
The  reader  is  referred  to  Knight's  Mechanical  Dictionary, 
article  "  Thermostats,"  and  to  Peclet's  "  Traite  du  la  Chaleur," 
Vol.  II,  for  a  description  of  many  of  the  early  forms  used. 
Those  which  are  in  use  may  be  classified  either  according  to 
the  general  character  of  the  thermostat  or  the  construction 
of  the  motor  employed  to  operate  the  heat-regulating  valves 
as  follows  : 

f  Moved  by  f  N    auxili          f  Expansion  or 

expansion  or  ^      contraction. 


change  of  M  I    Water. 

pressure.  \   Compressed 

L      air. 

165.    Regulators  Acting  by  Change  of  Pressure.  —  A 

change  of  temperature  acting  on  any  liquid  or  gaseous  body 
causes  a  change  in  volume,  which  in  some  instances  has  been 
utilized  to  move  the  heat-regulating  valves  so  as  to  maintain 
a  constant  temperature.  Fig.  220  represents  a  regulator  in 
which  the  expansion  or  contraction  of  a  body  of  confined  air  is 
utilized  to  control  the  motion  of  the  dampers  to  a  hot-water 
heater. 

It  consists  of  a  vessel  containing  in  its  lower  portion  a 
jacketed  chamber  connected  to  the  hot-water  heater  at  points 
of  different  elevation  so  as  to  secure  a  circulation  from  the 
heater  through  the  lower  portion  or  jacket  of  the  vessel  from 
2  to  3.  Above  this  is  a  second  chamber  which  is  covered  on 
top  with  a  rubber  diaphragm,  and  which  contains  a  funnel- 
shaped  corrugated  brass  cup.  The  opening  to  the  cup  is  in 


312 


HEATING   AND    VENTILATING   BUILDINGS. 


the  lower  portion  of  the  chamber,  the  top  and  larger  surface 
resting  against  the  rubber  diaphragm.  Enough  water  at 
atmospheric  pressure  or  alcohol  is  poured  into  the  upper 
chamber  through  the  opening  marked  I  to  seal  the  orifice  in 


FIG.  220. — LAWLER  HOT-WATER  DAMPER-REGULATOR. 

the  inverted  cup  and  confine  the  air  it  contains.  The  reg- 
ulator acts  as  follows :  The  warm  water  from  the  heater  mov- 
ing through  the  lower  chamber  communicates  heat  to  the 
water  or  alcohol  in  the  upper  chamber,  which  in  turn  warms 
the  air  in  the  inverted  cup,  causing  it  to  expand.  This  moves 
the  rubber  diaphragm  and  connected  levers  leading  to  the 
dampers  substantially  as  in  the  damper-regulator  for  steam- 
heaters,  already  described. 

The  Powers  regulator  for  hot-water  heaters  (see  Fig.  221) 
is  somewhat  similar  in  construction  to  the  one  described,  but 
acts  on  a  different  principle.  A  liquid  which  will  vaporize  at  a 
lower  temperature  than  that  of  the  water  in  the  heater  is  placed 
in  the  vessel  communicating  with  the  diaphragm,  in  which 
case  considerable  pressure  is  generated  before  the  water  in  the 
heater  reaches  the  boiling-point.  As  the  water  in  the  heater  is 
usually  under  a  pressure  of  5  to  10  pounds  per  square  inch,  its 
boiling  temperature  is  from  225  to  240  degrees,  water  of  at- 
mospheric pressure  which  boils  at  212°  can  be  used  in  the  closed 
vessel,  and  will  generate  considerable  pressure  before  that  ip 
the  heater  boils. 


TEMPERATURE  REGULATORS. 


313 


The  method  of  construction  is  shown  at  the  right,  in  Fig. 
22 1 ,  as  applied  to  a  hot-water  heater.  The  diaphragm  employed 
consists  of  two  layers  of  elastic  material  with  compartments  be- 
tween and  beneath  ;  the  lower  one  is  connected  to  the  chamber 


i  2  3 

FIG.  221. — THE  POWERS  THERMOSTAT  FOR  HOT- WATER  HEATERS. 


A,  which  is  filled  with  water  at  atmospheric  pressure  and  is  sur- 
rounded by  the  hot  water  flowing  from  the  heater.  The  water 
in  chamber  A,  being  under  less  pressure,  will  boil  before  that  in 
the  heater,  and  will  produce  sufficient  pressure  to  move  the 
diaphragm  and  levers  so  as  to  close  the  dampers,  before  the 
water  in  the  heater  reaches  the  boiling-point.  The  compart- 
ment between  the  two  diaphragms  f,  f  is  in  communication 
with  a  vessel  D,  which  in  turn  is  connected  by  a  closed  pipe  E 
with  a  thermostat,  which  may  be  placed  at  any  point  in  the 
house  and  so  arranged  that  if  the  temperature  becomes  too 
high  in  that  room,  the  dampers  of  the  heater  will  be  closed. 
With  this  apparatus  the  dampers  are  closed  either  by  excessive 
temperature  of  water  at  the  heater  or  too  great  a  heat  in  any 
room.  The  intermediate  compartment  is  only  required  when 
the  dampers  are  to  be  operated  by  change  of  temperature  in 
the  rooms. 

The  thermostat  employed  in  this  apparatus  consists  of  a 
vessel  2,  Fig.  221,  separated  into  two  chambers  by  a  diaphragm  ; 
one  of  these  chambers,  B,  is  filled  with  a  liquid  which  will 
boil  at  a  temperature  below  that  at  which  the  room  is  to  be 
maintained ;  the  other  chamber,  A,  is  filled  with  a  liquid  which 


HEATING   AND    VENTILATING   BUILDINGS. 


FIG.  222.— ELEVATION  OF  THERMOSTAT- 


does  not  boil,  and   is  connected  by  a  tube  to  a  diaphragm 

damper-regulator  which  moves  the  dampers  through  the  me- 

dium of  a  series  of  levers. 

Fig.  221,  2,  shows  a  transverse  section  and  I   an  elevation 

with  parts  broken  away  of  a  thermostat,  and  Fig.  222  an  ele- 

vation with  attached  ther- 
mometer. The  vapor  of  the 
liquid  in  the  chamber  B  pro- 
duces considerable  pressure 
at  the  normal  temperature 
of  the  room,  and  a  slight 
increase  of  heat  crowds  the 
diaphragm  over  and  forces 
the  liquid  in  the  chamber 
A  outward  through  a  con- 
necting tube  which  leads 
to  the  damper  -  regulator, 
one  form  of  which  has  been 
described. 
The  damper-regulator  as  applied  to  a  steam-heater  is  pro- 

vided with  a  single  rubber  diaphragm  with  the  parts  arranged 

as  shown  in   the  sec- 

tional  view  Fig.  223. 

In  this  case  the  liquid 

pressure      is     applied 

above  the  diaphragm, 

its  weight  being  coun- 

terbalanced by  springs 

and  weights,  attached 

to  the  levers. 

The  liquid  used  in 

the  thermostat  may  be  any  which  has  a  boiling  temperature 

somewhat  below  that  at  which  the  room  is  to  be  kept.     Many 

liquids  are  known  which  fulfil  this  condition,  of  which  we  may 

mention  etheline,  bromine,  various  petroleum  distillates,  anhy- 

drous ammonia,  and   liquid   carbonic   acid.     The   liquids  em- 

ployed in  the  Powers  thermostat  are  said  to  give  pressures  as 

follows  at  the  given  temperatures  : 


FlG>  M—  DIAPHRAGM  DAMPER-REGULATOR. 


TEMPERATURE  REGULATORS.  31$ 

At    6oc  ......  ......      I     pound  to  the  square  inch. 


70°  ............      4        "  " 


"     90°   ..........    10        "          "  "         " 

"     100°    ...........     13  "  "  " 

166.  Regulators    Operated    by    Direct    Expansion.— 

VIetals  of  various  kinds  expand  when  heated  and  contract 
vhen  cooled,  and  this  fact  has  often  been  utilized  in  the  con- 
struction of  temperature  regulators. 

A  single  bar  of  metal  expands  so  small  an  amount  that  it  is 
of  little  value  for  this  purpose  unless  very  long,  or  unless  its 
expansion  is  multiplied  by  a  series  of  levers.  Several  forms 
lave  been  used,  of  which  may  be  mentioned  :  a  bent  rod  with 
ts  ends  confined  so  that  expansion  tends  to  change  its  curva- 
ture ;  a  series  of  bent  rods  of  oval  form  resting  on  each  other 
with  the  ends  confined  between  two  fixed  bars  ;  two  metallic 
Dars,  having  different  rates  of  expansion  arranged  parallel  and 
the  variation  in  length  multiplied  by  a  series  of  connecting 
evers  an  amount  sufficient  to  be  available  in  moving  dampers  ; 
two  strips  of  metal  of  different  kinds  bent  into  the  form  of  an 
arc  and  fastened  together  so  as  to  form  a  curved  bar,  with 
the  metal  which  expands  at  the  greater  rate  on  the  inside,  so 
that  expansion  tends  to  straighten  it  when  heated  ;  the  differ- 
ence in  expansion  between  an  iron  rod  which  is  not  heated 
and  the  flow-pipe  of  a  hot-water  heater  multiplied  by  means 
of  a  series  of  levers.  The  constructions  described  above 
lave  all  been  tried  for  the  purpose  of  moving  the  dampers  of 
icaters  or  for  opening  and  closing  valves.  In  general,  how- 
ever, they  have  not  proved  satisfactory,  because  of  the  slight 
motion  caused  by  expansion,  and  the  uncertainty  of  operation 
obtained  with  multiplying  devices. 

Certain  organic  materials  have  the  property  of  bending  or 
curling  when  heated,  and  this  has  been  utilized  in  the  construction 
of  the  Howard  regulator.  This  regulator  consists  of  a  ther- 
nostat  in  the  form  of  a  plaque  of  triangular  form  n  inches 
ong  and  9  inches  wide  (Fig.  224),  which  is  located  in  any 


316  HEATING  AND    VENTILATING  BUILDINGS. 

living-room.  As  the  temperature  of  the  room  increases  the 
plaque  bends.  It  is  connected  by  means  of  cords  running  over 
pulleys  to  a  very  light  and  easily  moved  cylinder  damper 
arranged  so  as  to  regulate  both  fire  and  check  drafts.  The] 
damper  used  in  connection  with  this 
thermostat  consists  of  a  slotted  cylinder 
rotating  on  the  inside  of  a  tube  which 
leads  in  one  direction  to  the  ash-pit  and 
in  the  other  to  the  smoke-pipe.  A  parti- 
tion separates  the  two  parts  of  the  tube, 
and  the  slots  in  the  cylindric  damper  are 
so  arranged  that  when  the  connection  for' 
air  to  the  furnace  is  open  the  other  is 
closed,  and  vice  versa,  a  very  slight  motion 
serving  to  completely  open  or  close  the 
damper.  The  cylinder  damper  is  con- 
nected to  the  plaque  by  a  cord,  and  is  so 
arranged  that  the  drafts  are  opened  by 

FIG.  224.— HOWARD      the  motion  of  the  thermostat  and  closed 

THERMOSTATIC  PLAQUE.     , 

by  gravity. 

The  direct  expansion  of  a  liquid  or  of  a  gas  in  a  confined 
vessel  has  also  been  utilized  to  move  a  diaphragm  or  piston 
which  is  connected  by  levers  to  the  dampers  of  heaters,  in 
a  manner  similar  to  that  described  in  the  preceding  article. 
The  writer  at  one  time  constructed  a  regulator  for  a  hot-water 
system  in  which  the  expansion  of  water  in  a  closed  vessel  sur- 
rounding the  return-pipe  was  employed  to  operate  a  damper- 
regulator  similar  to  those  used  in  steam-heating,  page  156. 
Peclet  describes,  regulators  in  which  the  expansion  of  air  was 
employed  to  move  a  piston  connected  by  cords  and  pulleys  to 
the  dampers. 

167.  Regulators  Operated  with  Motor — General  Types. 
— The  regulators  which  have  been  described  in  the  preceding 
articles  operate  the  regulating  valves  with  a  feeble  force  acting 
through  a  considerable  range,  or  with  a  considerable  force  act- 
ing through  a  short  distance.  They  are  consequently  liable  to 
be  rendered  inoperative  by  any  accident  to  the  levers  or 
connecting  tubes,  or  by  any  cause  which  renders  the  valves 
difficult  to  operate.  To  overcome  such  difficulties  several 


TEMPERATURE   REGULATORS.  3 IJ 

systems  have  been  devised  in  which  the  power  for  operating 
the  dampers  should  be  obtained  from  an  independent  source, 
and  in  which  the  work  required  of  the  thermostat  would  be 
simply  that  of  starting  and  stopping  an  auxiliary  motor.  In 
the  first  systems  of  this  kind  the  motor  employed  was  a  system 
of  clockwork  which  had  to  be  wound  at  stated  intervals  in 
order  to  supply  the  force  required  for  moving  the  dampers. 
In  recent  systems  electricity,  water,  or  compressed  air  is 
employed  to  generate  the  power  required,  and  in  some  instances 
regulators  are  arranged  to  operate  not  only  the  valves  which 
supply  heat  to  the  rooms,  but  also  the  various  dampers  for  sup- 
plying hot  or  cold  air  in  the  ventilating  system. 

In  all  of  the  early  forms  of  this  kind  of  regulator  the 
thermostat  consisted  of  a  tube  of  mercury  or  a  curved  strip, 
made  of  two  metals  of  different  kinds  soldered  together  and 
arranged  so  that  a  given  change  of  temperature  would  pro- 
duce sufficient  motion  to  make  or  break  electric  contact.  A 
current  was  obtained  from  a  battery,  and  connecting  wires  led 
to  the  motor  and  to  the  various  terminals.  When  electric  con- 
tact was  made  at  a  position  corresponding  to  the  highest 
temperature,  the  current  would  flow  in  a  certain  direction  and 
cause  a  magnet  to  release  a  pawl  which  would  start  a  motor 
revolving  in  the  proper  direction  for  closing  the  valves. 
When  the  temperature  fell  below  a  certain  point,  the  thermo- 
stat would  make  electric  connections  so  that  the  current 
would  flow  in  the  opposite  direction  and  cause  the  motor  to 
reverse  its  motion,  thus  opening  the  valve.  If  the  motor  was 
operated  by  water,  the  electric  current  would  open  and  close 
a  valve  in  the  supply-pipe ;  if  the  motor  was  operated  by 
electricity,  the  current  from  the  battery  would  move  a  switch 
on  the  wires  leading  to  the  motor. 

The  valves  for  regulating  the  heat-supply  are  made  in  a 
great  variety  of  ways.  Dampers  for  regulating  the  flow  in 
chimneys  or  flues  are  generally  plain  disks,  balanced  and 
mounted  on  a  pivot,  so  that  they  may  be  turned  very  easily; 
globe-  or  gate-valves  are  usually  employed  in  steam-pipes 
and  must,  to  give  satisfactory  service,  either  be  closed  tight 
or  opened  wide.  A  system  in  which  steam-valves  are  oper- 
ated requires  much  more  power  than  one  in  which  dampers 
only  are  moved. 


HEATING   AND    VENTILATING   BUILDINGS. 


Many  systems  of  heat-regulation  employing  motors  are 
in  use  and  are  doubtless  worthy  an  extended  notice,  but  space 
will  only  permit  a  short  description  of  the  one  in  most  ex- 
tensive use  in  the  larger  buildings  of  this  country,  namely,  the 
Johnson  system  of  temperature  regulation. 

168.  Pneumatic  Motor  System. — In  the  Johnson  system 
of  heat-regulation  the  motive  force  for  opening  or  closing  the 
valves  which  regulate  the  heat-supply  is  obtained  from  com- 
pressed air  which  is  stored  in  a  reservoir  by  the  action  of  an 
automatic  motor.  The  thermostat  acts  with  change  of  tem- 
perature to  turn  off  or  on  the  supply  of  compressed  air. 
When  the  air-pressure  is  on,  the  valves  supplying  heat  are 
closed;  when  off,  they  are  opened  by  strong  springs.  The 
detailed  construction  of  the  parts  are  as  follows : 

The  compressed  air  is  supplied  by  an  automatic  air-com- 
pressor which  is  operated  in 
small  plants  by  water-pressure 
and  acts  only  when  the  supply 
of  compressed  air  has  fallen  be- 
low the  limit  of  pressure.  The 
external  form  of  the  air-com- 
pressor is  shown  in  Fig.  225.  It 
consists  of  a  vessel  divided  into 
two  chambers  by  a  diaphragm  ; 
one  chamber  is  connected  to  the 
water-supply,  the  other  to  the 
atmosphere.  The  water  enter- 
ing' on  one  side  crowds  the  dia- 
phragm over  until  a  certain 
position  is  reached  when  the 
supply-valve  is  closed  and  a 
discharge-valve  is  opened,  after 
which  the  diaphragm  returns  to 
its  original  place.  The  motion 
of  the  diaphragm  backward  and 
forward  serves  to  draw  in  and 
discharge  air  from  the  other 
chamber  in  a  manner  similar  to  the  operation  of  a  piston-pump, 
valves  being  provided  on  both  inlet-  and  discharge-pipes. 


FIG.    225.  —  EXTERNAL    VIEW 
SMALL  AIR-COMPRESSOR. 


OF 


TEMPERATURE  REGULATORS. 


319 


When  the  air-pressure  reaches\a  certain  amount,  the  pump 
ceases  its  operation. 

An  air-pipe  leads  from  the  air-compressor  to  the  thermostat, 
and  another  from  the  thermostat  to  the  diaphragms  in  con- 
nection with  valves  or  dampers.  The  action  of  the  thermo- 
stat, as  already  explained,  is  simply  to  operate  a  minute  valve 
for  supplying  or  wasting,  as  necessary,  compressed  air  in  the 
pipe  leading  from  the  thermostat  to  the  diaphragm-valves. 

Fig.  226  is  a  sectional  view  of  the    diaphragm-valve,  the 


FIG.  226. — SECTIONAL  VIEW  OF  DIAPHRAM- 
VALVE. 


FIG.  227.— DAMPER  FOR  HOT- 
AND  COLD-AIR  FLUE. 


compressed  air  being  admitted  above  the  valve  and  acting 
merely  to  close  it.  It  can  also  be  closed  if  necessary  by  hand. 
The  compressed  air  can  also  be  made  to  operate  dampers  of 
which  various  styles  are  used,  and  these  may  be  placed  in  ven- 
tilating flues,  hot-air  pipes,  or  smoke-flues,  and  so  arranged  as 
to  admit  either  warm  or  cold  air  alternately  to  a  room,  as 
may  be  required  to  maintain  a  uniform  temperature.  Fig.  227 
shows  a  damper  for  two  round  flues,  one  for  cold  air,  the  other 


320 


HEATING   AND    VENTILATING   BUILDINGS. 


for  hot,  connected  to  a  diaphragm  and  arranged  so  that  when 
one  is  open  the  other  will  be  closed. 

This  system  of  heat-regulation  has  been  brought  to  a  very 
high  degree  of  perfection,  and  if  sufficient  heat  is  supplied  the 
temperature  of  a  room  is  maintained  with  certainty  within  one 
degree  of  any  required  point.  Farther  than  that,  the  system 
is  so  arranged  that  after  all  the  rooms  of  the  house  reach 
the  desired  temperature  the  heat-regulator  then  acts  to  close 
the  furnace-dampers.  The  apparatus  is  in  extensive  use  for 
regulating  temperature  in  the  hot-blast  system  of  heating. 
Fig.  228  shows  the  method  adopted  of  applying  a  damper- 
regulator  to  a  stack  for  indirect  heating  which  is  so  arranged 
as  to  admit  either  warm  or  cool  air  as  necessary  to  maintain 
a  uniform  temperature. 


FIG.  228. — DOUBLE  DAMPER  IN  BRICK  DUCT. 

169.  Saving  Due  to  Temperature  Regulation. — The  ex- 

.pense  of  constructing  a  perfect  system  of  heat-regulation  is 
imet  in  a  short  time  by  the  saving  in  fuel  bills.  The  writer 
recently  examined  the  records  of  the  fuel  consumed  in  a  build- 
ing when  heated  for  a  series  of  years  without,  and  afterwards 
with,  the  heat-regulating  system.  He  also  examined  the  records 
showing  the  coal  consumed  in  two  buildings  of  exactly  the 
same  size  and  class,  in  the  same  city,  and  as  nearly  as  possible 
with  the  same  exposure.  In  both  these  cases  the  saving  was 
somewhat  over  35  per  cent  annually  of  the  cost  of  the  regu- 
lating apparatus. 

The  saving  in  any  given  case  must,  of  course,  depend  upon 


TEMPERA  TURE  REG  ULA  TORS. 


321 


conditions  and  how  carefully  the  drafts  are  regulated  under 
ordinary  systems  of  operation.  Usually,  when  the  temperature 
is  regulated  by  hand,  the  rooms  are  allowed  to  become  alter- 
nately hot  and  cool,  but  a  greater  portion  of  the  time  they  are 
much  warmer  than  is  necessary,  and  frequently  windows  are 
opened  for  the  escape  of  the  extra  heat.  The  maintenance  of 
a  uniform  temperature  for  such  cases  means  a  saving  of  fuel 
by  utilizing  the  heat  better,  and  usually,  also,  by  a  more  perfect 
combustion  of  fuel.  It  would  seem  from  these  considerations 
that  a  reasonable  estimate  of  the  saving  obtained  by  the  use  of 
a  perfect  temperature  regulator,  as  compared  with  ordinary 
regulation,  would  run  from  15  to  35  per  cent  of  the  fuel  bills 
per  year. 

Construction  of  Pneumatic  Thermostat.— The  following 
diagram  and  explanation  will  render  the  principle  of  action  of 


RESERVOIR 

a 


THERMOSTAT 

b 

FIG.  229. — DIAGRAM  ILLUSTRATING  THE  PNEUMATIC  THERMOSTAT. 

the  pneumatic  thermostat  as  employed  in  the  Johnson  system 
of  heat  regulation  intelligible. 

Fig.  229  shows  to   different   scales  the  reservoir  for  com- 
pressed air,  a  diagram  of  the  thermostat  and  of  a  diaphragm 


3  2 1  a         HE  A  TING   A  ND    VEN  TIL  A  TING   B  UIL  D  ING  S. 

for  operating  dampers.  The  thermostat  is  drawn  relatively  to 
a  very  large  scale.  The  temperature  regulator  as  a  whole  con- 
sists first  of  an  air  compressor,  as  shown  in  Fig.  225,  or  one  of 
similar  construction,  and  arranged  so  as  to  maintain  a  constant 
pressure  in  air  reservoir  R  or  in  the  pipes  of  the  building. 

The  principle  of  operation  of  the  thermostat  is  illustrated 
by  the  diagram,  although  the  details  of  construction  of  the  act- 
ual instrument  are  quite  different.  Compressed  air  from  the 
reservoir  or  air-pump  passes  through  the  pipe  A  to  the  cham- 
ber B,  thence,  if  the  double  valve  ab  is  open,  it  will  pass  out 
through  the  pipe  C  to  the  chamber  V  above  the  diaphragm. 
Its  pressure  then  causes  the  end  X'  of  the  lever  X' X  to  move 
downward.  This  lever  is  connected  to  the  damper  in  such  a 
manner  as  to  close  off  the  supply  of  heat  when  in  the  lowest 
position.  If  the  room  becomes  too  cold,  mechanism  to  be 
hereafter  described  moves  the  valve  ab  into  such  a  position  as 
to  close  the  communication  to  the  compressed  air  in  the  cham- 
ber B  and  open  communication  with  the  atmosphere  at  b.  This 
permits  the  air  to  escape  from  the  chamber  V,  through  the 
pipe  C  and  opening  b,  into  the  air,  the  diaphragm  in  the  lower 
part  of  the  chamber  V  being  moved  upward  by  a  spring  or 
weight  not  shown  in  the  sketch.  Thus  it  is  seen  that  by  mov- 
ing the  double  valve  ab  the  chamber  Fisput  in  communication 
with  the  compressed  air  and  the  damper  moved  to  close  off  the 
heat,  or  with  the  outside  air,  in  which  case  the  pressure  in  the 
chamber  Fis  lessened  and  the  damper  is  moved  by  action  of  a 
weight  or  a  spring  so  as  to  admit  the  warm  air. 

The  mechanism  for  moving  the  valve  ab  consists  of  a 
thermostat  T,  which  may  be  made  of  any  two  materials  having 
a  different  rate  of  expansion,  as  rubber  and  brass,  zinc  and 
brass,  etc.  Connected  to  the  thermostatic  strip  is  a  small 
valve  Kj  so  adjusted  that  when  the  room  is  too  warm  the  valve 
will  be  opened  and  when  too  cold  it  will  be  closed  by  the  ex- 
pansion and  contraction  of  the  thermostatic  strip.  Suppose 
the  room  too  warm  and  the  valve  K  open,  air  then  flows 
through  the  chamber  B,  through  the  filtering  cotton  in  the 
lower  part  of  B' ,  thence  through  the  small  tube  </and  the  valve 
K  to  the  air.  The  small  tube  d  connects  with  an  expansible 
chamber  D  and  opens  back  of  a  small  diaphragm.  When  the 


TEMPERATURE   REGULATORS. 

valve  K  is  open  the  spring  5  forces  the  diaphragm  into  the 
contracted  or  collapsed  position,  causing  the  lever  GFto  move 
the  valve  ab  so  as  to  put  the  chamber  B  in  communication  with 
chamber  V  and  permit  the  air-pressure  to  close  the  damper 
connected  to  the  lever  X' X.  If,  however,  the  room  becomes 
too  cold,  the  thermostat  T  moves  so  as  to  close  the  valve  K\ 
this  stops  the  escape  of  air  from  the  pipe  dand  causes  sufficient 
pressure  to  accumulate  under  the  diaphragm  at  D  to  move  the 
lever  FG,  so  as  to  move  ab  to  the  left,  thus  cutting  off  the  sup- 
ply of  compressed  air  from  the  chamber  Fand  permitting  the 
air  to  escape  at  b.  It  will  be  noted  that  air  is  continually 
escaping  at  K  during  the  time  the  room  is  too  hot,  but  this  is 
a  very  short  interval  as  compared  with  the  entire  time,  and 
moreover  the  orifice  at  K  is  exceedingly  small,  so  that  the  loss 
of  air  is  quite  insignificant.  It  will  also  be  noted  that  with  this 
apparatus  the  damper  is  quickly  moved  from  a  position  fully 
open  to  shut,  or  vice  versa,  and  that  it  will  not  stand  in  an 
intermediate  position  fully  open  or  fully  shut. 

The  manufacturers  of  the  Johnson  thermostat  have  quite 
recently  designed  an  instrument  which  will  move  the  adjusting 
damper  connected  to  the  line  XX'  slowly  and  will  hold  it  in 
any  intermediate  position  as  desired.  This  is  considered  an 
advantage  for  systems  of  ventilation  in  which  it  is  always  de- 
sired to  admit  the  same  volume  of  air,  but  in  which  the  relative 
amounts  of  hot  and  cold  air  are  varied  to  maintain  the  desired 
temperature. 


CHAPTER   XVI. 
SPECIFICATION  PROPOSALS  AND  BUSINESS  SUGGESTIONS. 

170.  General  Business  Methods.  —  Nearly  all  heating-  \ 
plants  are  constructed  by  contractors,  who  agree  for  a  specified 
sum  to  install  a  heating-plant  in  accordance  with  certain  speci- 
fications, or,  in  absence  of  specifiations,  one  which  is  guaranteed 
to  fulfil  certain  stipulations  as  to  warming  and  ventilating  in 
any  stress  of  weather.  Specifications  are  prepared  either  by  a 
disinterested  third  party  who  is  thoroughly  familiar  with  the 
subject,  or  by  the  party  submitting  the  proposal.  The  first 
method,  although  not  common  except  in  the  case  of  large 
buildings,  is,  when  the  specifications  are  properly  drawn,  satis- 
factory both  to  the  owner  and  the  contractor.  With  proper 
specifications  estimates  can  be  obtained  from  different  bidders 
on  work  of  the  same  class  and  quantity,  and  this  is  likely  to 
result  in  a  better  quality  of  work,  and  often  in  lower  prices. 
Where  each  contractor  bids  on  his  own  specifications  and 
arranges  for  apparatus  in  accordance  with  his  own  judgment,  • 
there  will  be  a  very  great  difference  in  the  quality  and  method 
of  construction  proposed,  which  is  likely  to  result  to  the  advan- 
tage of  an  unscrupulous  bidder,  who  would,  if  possible,  use 
cheap  material  and  the  least  possible  quantity  of  heating  and 
radiating  surface.  It  is  for  these  reasons  to  the  advantage 
of  all  concerned  that  full  and  complete  specifications  should  be 
provided  which  will  show,  accurately,  the  character,  amount 
and  quality  of  the  required  work. 

The  specifications  may  be  written  as  a  part  of  the  tender 
for  the  work,  or  as  an  independent  document  to  which  reference 
is  made  in  the  proposals. 

The  specifications  are  often  accompanied  with  drawings 
which  show  the  location  of  all  the  principal  parts  of  the  heat- 
ing apparatus  and  frequently  many  details  of  construction  ;  the 

322 


SPECIFICATION  PROPOSALS— SUGGESTIONS.  323 

drawings  are  considered  in  every  case  a  portion  of  the  specifica- 
tions and  are  equally  binding  on  the  contractor. 

After  the  bid  has  been  accepted  a  contract  is  drawn  which 
should  contain  a  full  statement  of  the  agreement  between  con- 
tractor and  owner,  and  of  all  conditions  relating  to  the  method 
of  payment,  penalties,  time  of  completion  of  work,  etc. 

J.  J.  Blackmore  and  J.  G.  Dudley,  New  York,  acting  as  a 
committee  appointed  by  the  National  Association  of  Manu- 
facturers of  Heating  Apparatus,  have  given  the  matter  relating 
to  uniform  specifications  much  study,  and  we  are  indebted  to 
them  for  the  following  discussion,  and  also  for  the  copy  of  the 
uniform  proposals  here  submitted. 

171.  General  Requirements.* — "  It  is  not  within  the  scope 
of  a  work  such  as  this,  nor  have  the  trade  conditions  in  the 
heating  business  advanced  to  such  a  point,  that  all  the  details 
of  any  or  every  system  can  be  provided  for.  The  following 
proposed  form  for  uniform  standard  specifications,  however, 
covers  the  ground  as  fully  as  can  be  done  at  this  time,  as  is 
shown  by  the  recommendation  by  the  National  Association 
of  Manufacturers  of  Heating  Apparatus,  and  if  generally 
accepted  by  heating  contractors,  manufacturers,  architects, 
investors,  and  the  laymen  installing  steam  or  hot-water  heat- 
ing apparatus,  would  result  in  a  higher  standard  of  excellence. 
Much  trouble  now  exists  in  securing  best  results,  due  to 
ignorance  on  part  of  owner,  architect,  or  contractor,  as  well  as 
to  unfair  competition  or  unauthorized  substitutions  of  'cheap' 
materials. 

"  Any  specification  should  set  forth  unequivocally  and  in 
detail  (as  far  as  feasible)  all  that  the  contractor  is  to  furnish 
and  exactly  what  is  to  be  accomplished  by  his  guarantee,  which 
should  embody  a  standard  of  economy  as  well  as  one  of 
efficiency.  The  function  of  the  owner  or  architect  is  to  stipulate 
what  results  must  be  accomplished  according  to  standards  in 
accepted  use,  and  to  give  the  consulting  engineer  (when  char- 
acter of  heating-plant  demands  one)  or  the  contractor  proper 
latitude  as  to  methods  to  be  pursued.  Further  than  this,  it  is 
the  office  of  owner  or  architect,  in  justice  to  himself  and  to 
competing  bidders,  as  well  as  to  the  successful  contractor,  to 

*  Written  for  this  work  by  J.  J.  Blackmore  and  J.  G.  Dudley. 


324  HEATING   AND    VENTILATING   BUILDINGS. 

see  that  the  provisions  of  the  specifications  are  carried  out,  and 
that  the  quantity  and  character  of  material  agreed  upon  are 
actually  furnished  and  used.  Certificates  to  that  end  should 
be  demanded  and  given,  if  it  is  deemed  necessary,  since  much 
injury  is  done  to  a  legitimate  and  beneficial  calling  by  what  is 
termed  *  skinning  the  job/  that  is,  agreeing  to  furnish  certain 
things  and  then  by  taking  advantage  of  May'  ignorance  sub- 
stituting inferior  goods  or  omitting  them  outright. 

"As  already  shown,  the  attainment  of  certain  results  follows 
from,  and  is  accomplished  by,  scientific  and  mathematical  proc- 
esses, whether  actually  figured  and  reasoned  out,  or  arrived  at 
by  *  rule  of  thumb,'  as  many  really  excellent  contractors  are 
known  to  do. 

"  In  illustration,  imagine  a  country  residence  in  course  of 
erection  after  plans  by,  and  under  supervision  of,  a  competent 
architect,  and  note  how  a  proper  heating-plant  is  installed.  To 
begin  with,  the  owner  should  learn  from  his  architect  or  from 
any  other  properly  informed  person  that  the  desired  efficiency, 
sufficiency,  and  results  to  be  procured  by  the  heating  system 
depends  more  on  amount  of  investment  than  on  anything  else. 
For  instance,  the  same  results  can  be  achieved  by  employ- 
ing either  steam  or  water.  The  first  cost,  however,  is  less 
with  steam,  while,  it  is  contended  by  many,  the  running  and 
ultimate  cost  is  less  with  water.  The  reason  for  this  is  that 
with  the  hot-water  system  as  usually  installed,  with  an  open 
tank  for  expansion  of  water,  the  temperature  of  the  heating 
medium  ranges  from  150°  to  200°  F.,  while  with  steam  it 
ranges  from  212°  to  240°  F.;  as  a  consequence  more  radiating 
surface  is  needed  for  the  former  than  for  the  latter. 

"  To  continue  the  illustration,  let  the  owner  select  steam, 
and  also  suppose  that  he  elects  to  have  indirect  heating  on 
ground-floor,  to  obtain  extra  ventilation  (for  be  it  understood 
that  some  ventilation,  accidental  or  otherwise,  is  absolutely 
necessary  to  obtain  right  heating  results),  while  on  the  upper 
floors  he  chooses  direct  heating.  This  done,  it  then  devolves 
on  the  engineer,  contractor,  or  architect  to  determine  the 
respective  amounts  of  heating  surfaces  required  to  warm  the 
several  rooms  to  the  indicated  temperature  according  to  an 
accepted  standard.  Much  harm  at  present  results  from  de- 


SPECIFICATION  PROPOSALS— SUGGESTIONS.  3*5 

manding  and  permitting  the  several  bidders  to  estimate  on 
different  amounts  of  heating-surface  for  exactly  the  same  work. 
The  minimum  amount  should  be  determined  by  some  one 
individual,  who  should  be  recompensed  for  this  service,  and  he 
alone  held  responsible  for  this  estimate.  The  owner  or  archi- 
tect should  indicate  on  the  building  plans  where  surfaces  shall 
be  placed,  bearing  in  mind  always  the  room  required  in  the 
allotted  spaces  and  also  the  requirements  of  the  system.  This 
is  necessary  for  the  contractor  to  know,  since  on  it  depend 
[the  number  of  his  riser-lines  and  the  amount  of  piping  in  his 
boiler-room. 

"  When  feasible,  the  owner  or  architect  should  indicate  all 
the  '  specialties '  desired  in  the  apparatus,  and  each  bidder 
should  be  compelled  to  figure  as  nearly  as  possible  on  exactly 
the  same  set  of  specifications.  This  method  is  just  to  those 
who  estimate  in  good  faith,  and  usually  closer  and  lower  figures 
will  be  obtained  by  the  owner.  The  contractor,  with  these  data 
before  him,  takes  dimensions  either  from  the  architect's  plans 
:or  from  the  measurements  of  the  building  itself ;  he  then  com- 
putes the  quantity  and  cost  of  all  materials  which  will  be  used  in 
ithe  completed  apparatus  ;  the  method  of  computation  varying 
I  from  that  of  pure  guesswork  or  shrewd  'estimating'  to  that 
'of  painstaking  measurement  and  actual  figuring  out  of  the 
exact  amount  of  stock  required,  together  with  its  purchasable 
cost  from  the  trade  catalogues  and  price-lists. 

"  To  the  net  cost  for  material,  including  boiler,  radiators, 
pipe,  fittings,  valves,  vents,  floor-  and  ceiling-plates,  registers, 
ducts,  covering,  painting,  bronzing,  smoke-pipe,  freight  and 
cartage,  board,  car-fares,  labor,  and  incidentals,  is  added  such  a 
margin  of  profit  as  the  contractor  considers  his  experience, 
reputation,  and  workmanship  are  entitled  to. 

"  In  justice  to  the  bidders  the  conditions  of  the  award 
should  be  clearly  set  forth  beforehand,  and  it  should  be  stated 
whether  this  work  will  go  to  the  lowest  bidder,  or  whether 
a  '  preference '  (often  justified)  is  to  be  given  a  certain  con- 
tractor. When  it  is  known  that  the  preparation  of  a  set  of 
specifications  and  of  an  estimate  of  cost  is  an  expense,  and 
often  not  a  small  one,  to  each  and  every  bidder,  the  injus- 
tice of  requiring  all  to  bear  this  instead  of  having  it  done 


326  HEATING   AND    VENTILATING   BUILDINGS. 

once  and  for  all  is  too  evident  for  argument.  It  is  for  this 
reason  that  a  uniform  standard  specification  is  recommended 
by  the  National  Association  of  Manufacturers  of  Heating 
Apparatus. 

"  Suppose  now  the  award  be  made  to  the  lowest  bidder, 
bids  having  been  made  on  the  same  set  of  specifications  which 
embody  full  statements  in  regard  to  requirements  of  the 
completed  plant.  The  owner  (or  architect)  and  the  contractor 
are  then  to  execute  a  proper  contract  for  the  performance  of 
the  work  and  for  the  payments  therefor.  Then  each  should 
be  required  to  fulfil  the  conditions  of  said  contract.  The 
National  Association  of  Master  Steam  and  Hot-water  Fitters 
has  adopted  a  uniform  standard  contract  which  seems  to  meet 
the  requirements  and  is  quite  generally  accepted  in  such  cases. 
The  form  is  given  below  and  may  be  obtained  of  the  secretary 
of  that  association. 

172.  Form  Proposed  by  the  National  Association  of 
Manufacturers  of  Heating  Apparatus. — For  a  steam-heat- 
ing plant. 

UNIFORM    STANDARD   SPECIFICATION   FOR  A  COMPLETE 

LOW-PRESSURE   STEAM   OR   HOT-WATER 

HEATING   APPARATUS. 

NOTE. — All  clauses  and  terms  in  this  type  and  enclosed  in  brackets  [] 
apply  only  to  hot  water.  All  clauses  and  terms  in  this  type  and  enclosed  in 
parenthesis  ( )  apply  only  to  steam.  Words  in  italics  are  to  be  supplied  in 
each  contract. 

TO   BE   INSTALLED  AND   ERECTED   COMPLETE   IN 
the  three-story  stone  and  frame  residence 

OWNED   BY 

/.  N.  Vestor,  No.  75  Broadway,  New  York  City, 

LOCATED    AT 
N.  W.  Corner  of  State  and  Hudson  Streets,  Yonkers,  N.  Y. 

THE   HEATING   SYSTEM 

shall  be  erected  according  to  the  single  pipe  method  of  (steam) 
[water]  heating,  the  (steam)  [water]  to  circulate  (under  a  press- 
ure) [at  a  temperature]  never  exceeding  (three  (3)  pounds  to  the 
square  inch  at)  [ degrees  F.  in  the  flow-pipes  of]  the  boiler, 


SPECIFICATION  PROPOSALS— SUGGESTIONS. 

conveyed  to  heating  surfaces  by  a  system  of  piping  so  erected 
that  all  water  (of  condensation)  in  the  system  shall  be  freely 
eturned  to  boiler  by  gravity  alone. 

(STEAM   GENERATOR.)      [WATER   HEATER.] 

The  (steam)  [water]  shall  be  (generated)  [heated]  by  one  No. 
2  Vertical  Tubular  Sectional  Boiler,  manufactured  by  C.  Iron  & 
Co.,N.  Y.  City,  and  by  them  guaranteed  free  from  all  flaws  and 
defects.  Said  boiler  to  have  a  grate  area  of  700  square  inches, 
capable  of  burning  all  kinds  of  coal  as  fuel,  and  guaranteed  by 
makers  to  be  capable  of  supplying  (steam)  [water]  to  750  net 
square  feet  of  direct  radiation  without  "  forcing  " ;  boilers  to 
be  certified  by  manufacturer  to  be  able  to  stand  a  cold-water 
pressure  of  80  pounds  to  the  square  inch. 

An  opening  not  less  than  two  (2)  feet  by  five  (5)  feet  into 
the  building  and  boiler-room  shall  be  provided  by  owner. 

BOILER   SETTING. 

Boiler  to  be  placed  as  near  smoke-flue  as  possible,  upon  a 
level  concrete  or  other  equally  solid  foundation  provided  by 
owner.  The  top  to  be  not  less  than  six — feet  from  ceiling  of 
boiler-room.  All  necessary  excavating  to  be  done  at  expense 
of  contractor. 

When  boiler  is  set  in  brickwork  same  shall  be  not  less  than 
eight  (8)  inches  thick,  erected  concentric  or  parallel  with  ex- 
ternal boiler  walls  as  shown  by  plans  of  manufacturer.  Brick 
to  be  hard  burned,  and  laid  in  courses  which  break  joints,  with 
cement  mortar  not  more  than  one-fourth  inch  in  thickness. 
Bond  courses  of  headers  to  be  laid  once  in  every  five  courses. 
Setting  when  complete  to  be  air-tight,  and  guaranteed  to  stand 
all  strains  of  expansion  and  contraction ;  or,  when  plastic 
covering  is  used  for  setting,  same  shall  be  evenly  distributed 
over  external  boiler  surfaces  not  less  than  two  (2)  inches  thick. 
The  ash-pit  shall  not  be  less  than  twelve  inches  deep,  and  shall 
be  sloped  to  edge  of  clean-out  door.  Boiler  shall  be  provided 
with  fire,  clean-out,  and  ash-pit  doors,  of  such  form,  size, 
structure,  and  set  in  such  position  as  shall  make  accessible  all 
portions  of  boiler  requiring  attention.  When  setting  of  boiler 
demands  it,  same  shall  be  provided  with  cast-iron  front  de- 


328  HEATING   AND    VENTILATING   BUILDINGS. 

signed  by  manufacturers  for  boiler  specified.  Same  to  be 
protected,  when  necessary,  from  direct  heat  of  flame  by  brick- 
work or  other  means  equally  good. 

FIXTURES,    FIRE   TOOLS,   AND   TRIMMINGS. 

Boiler  shall  be  provided  with  rocking  and  dumping  grates 
designed  by  manufacturers  for  boiler  specified,  together  with 
shaking-lever  and  all  fire  tools  necessary  to  care  for  same, 
which  shall  consist  of  one  (i)  poker,  one  (/)  slice-bar,  one  (/)  fine 
brush  and  handle.  Boiler  shall  be  provided  with  (one  5" 
brass-bound,  low-pressure  Bourdon  steam-gauge,  with  stop-cock 
and  siphon),  (one  (i)  low-pressure  safety-valve  with  ten  (10} 
pound  weight),  (one  (/)  water-column  fitted  with  two  (2)  brass  try- 
cocks)  [expansion  thermometer  registering  from  80  degrees  F.  to 
250  degrees  F.]  (one  Scotch  gauge-glass  and/<?#r  (4)  brass  guard- 
rods),  and  one  automatic  [  ]  damper  regulator  with  con- 
nections for  operating  draft-door  and  cold-air  check ;  one  i1/^ 
inch  brass  steam  (blow-off)  cock  with  key ;  and  there  shall  be 
provided  in  addition  to  above  all  pipe,  fittings,  and  valves 
necessary  to  render  connection  of  all  of  above  to  boiler  com- 
plete. 

WATER   CONNECTIONS   AND    BLOW-OFF. 

Feed-water  with  its  supply-pipe  shall  be  brought  within 
six  feet  of  boiler  by  owner,  and  left  with  one  ^Vrinch  cast-iron 
fitting  for  boiler  connection  to  be  made  by  contractor.  (Water 
supply  to  be  controlled  by  no  automatic  water-feed.)  Blow-off 
cock  to  be  located  at  lowest  point  of  system,  with  piping  so 
pitching  toward  same  as  to  allow  of  draining  boiler  and  of 
system,  same  to  be  fitted  for  a  hose-nipple  connection.  The 
discharge  to  waste  opening  (provided  by  owner)  shall  be 
always  visible. 

SMOKE-PIPE   AND   SMOKE-FLUE. 

Contractor  shall  connect  boiler  to  smoke-flue  opening  (pro- 
vided by  owner]  by  means  of  gas-tight  pipe  tivelve  inches 
in  diameter,  built  of  No.  14  galvanized  iron,  in  which  shall  be 
placed  one  (i)  shut-off  damper  with  wheel  handle  attached,  to- 
gether with  proper  clean-out  door.  Smoke-flue  throughout  to 
be  not  less  than  113  square  inches  internal  area,  and  46  feet  in 


SPECIFICATION  PROPOSALS— SUGGESTIONS.  329 

height,  straight,  and  presenting   no    unusual  obstructions  to 
gases.     Responsibility  for  proper  working  to  rest  on  owner. 

FLOW,    BRANCH,    AND   RETURN   MAINS. 

Flow-pipes  and  branches  shall  be  run  on  a  grade  to  or 
from  boiler  of  not  less  than  one  inch  fall  in  each  ten  feet  run ; 
size  of  pipes  to  be  of  such  area  as  to  quickly,  adequately,  and 
noiselessly  carry  (steam)  [water]  by  means  of  branches  and 
risers  to  heating  surfaces,  and  also  to  permit  an  unimpeded 
flow  of  all  (water  of  condensation)  [return  water]  to  or  from 
boiler  by  means  of  mains,  branches,  or  reliefs.  The  size  of 
pipes  shall  be  gauged  by,  and  shall  in  no  case  be  reduced 
below,  standards  laid  down  in  Carpenter's  "  Heating  and  Ven- 
tilating Buildings."  All  mains  are  to  be  so  run  in  straight 
lines,  and  junctions  so  made,  as  to  avoid  all  traps  or  pockets 
which  may  hold  air  or  (water  of  condensation).  (When  pitch  of 
pipes  brings  level  of  flow-mains  within  eighteen  inches  of  water- 
line  of  boiler,  establish  higher  level  for  steam-flow,  make  con- 
nection with  proper  relief,  so  as  to  drip  all  condensation.)  All 
expansion  and  contraction  of  pipes  throughout  system  must 
be  provided  for  in  joints  thereof  so  as  to  prevent  buckling  or 
bending  of  same,  and  all  joints  made  steam  and  water  tight. 
[Note. — No  bushings  shall  be  used  on  hot-water  flow-pipes, 
whether  mains,  risers,  or  radiator  connections.] 

This  system  of  piping  contemplates  three  (j)  flow-mains, 
il/t,  2,  and  2*/z  inches  diameter,  respectively,  pitching  from  the 
boilers.  There  shall  also  be  two  (2)  return-mains  pitching 
toward  the  boiler  on  a  grade  not  less  than  one  inch  in  (twenty) 
[fifteen]  feet  run  ;  same  to  be  carried  to  boiler  on  the  overhead 
plan,  and  to  be  so  connected  that  there  shall  be  tivo  (2)  re- 
turn-mains entering  boiler  of  not  less  than  one  and  one  quarter 
inches  in  diameter.  (Said  main  to  be  provided  with 
inch  swinging  check-valve  outside  the  boiler.) 

RISERS  (RELIEFS)  AND  CONNECTIONS. 

All  risers  shall  be  erected  plumb  and  straight,  and  all  con- 
nections thereto  shall  be  made  below  or  in  the  floors  by  means 
of  double  joints  to  allow  for  expansion.  When  "  offsetting  " 


33°  HEATING   AND    VENTILATING   BUILDINGS. 

or  coupling  parallel  lines  of  pipe,  care  shall  be  taken,  when 
possible,  to  locate  centres  of  like  pairs  of  fittings  at  same  verti- 
cal or  horizontal  level,  as  case  may  be.  Whenever  pitch  or 
size  of  pipes  does  not  allow  full  vent  of  contained  air  (or 
discharge  of  water  of  condensation)  proper  automatic  air-vents 
and  reliefs  or  drip-pipes  of  sufficient  size  (according  to  Carpen- 
ter's tables)  shall  be  used.  (When  air- vents  are  fitted  with 
drip-pipes  same  shall  be  run  plumb  and  straight  and  parallel 
with  risers,  or  return-riser  lines,  down  to  boiler-room,  where 
same  shall  be  joined  together  in  one  common  main,  which  shall 
there  vent  the  contained  air.)  No  drip-pipes  will  be  attached. 

The  within  system  contemplates  five  (5)  flow-risers  and  no 
return-risers. 

[EXPANSION- TANK  AND  CONNECTIONS.] 
To  be  omitted  in  steam-heating. 

[There  shall  be  furnished  and  connected,  at  a  point  not  less 
than  twelve  inches  above  highest  radiating  surface,  in  best  loca- 
tion which  conditions  of  building  permit,  one  gallon  gal- 
vanized-steel  expansion-tank,  fitted  with  gauge-glass  and 
brass  guard-rods.  Flow  connections  to  tank  shall  be  so 
made  as  to  maintain  a  circulation  of  contained  water  at  all  times 
when  apparatus  is  in  use.  Tank  shall  be  provided  with  a 
inch  pipe  for  venting  overflow,  same  to  be  arranged  to  waste  on 
roof  or  other  outlet.] 

FLANGES   AND   UNIONS. 

At  proper  points  on  mains,  branches,  and  return-mains 
shall  be  located  right  and  left  couplings  or  flange-unions,  so 
that  pipes  may  be  disconnected  without  injury  to  balance  of 
apparatus  or  system.  Couplings  may  be  used  on  all  pipes  up 
to  two  inches  in  size,  all  larger  pipes  to  be  united  with  flange- 
unions  made  tight  with  copper  gaskets. 

HANGERS. 

All  flow  and  return  pipes  shall  be  supported  by  chain  ad- 
justable pipe-hangers,  securely  fastened  to  building  at  intervals 


SPECIFICATION  PROPOSALS— SUGGESTIONS.  331 

of  not  more  than  ten  feet,  and  so  constructed  as  to  permit  free 
expansion  and  contraction  of  piping. 

FLOOR  AND   CEILING  PLATES,   AND    PROTECTION. 

Wherever  pipes  pass  through  floors,  floor-plates  shall  be 
used.  Wherever  pipes  pass  through  ceilings,  ceiling-plates 
shall  be  used,  unless  other  provision  for  finish  be  provided  for. 
All  protection  of  woodwork,  etc.,  from  heat  of  pipes  shall  be 
done  in  accordance  with  rules  and  regulations  of  National 
Board  of  Fire  Underwriters.  The  return  and  branch  mains 
and  connections  in  boiler-room  shall  be  covered  with  sectional 
asbestos  covering  one  inch  thick  [or  with  asbestos  paper, 
i"  Hair  Felt,  rosin-sized  paper,  and  canvas  neatly  sewed 

on,  to  prevent  waste  of  heat]. 

RADIATOR-VALVES  AND  AIR-VENTS. 

Each  direct  or  direct-indirect  radiator  or  coil  shall  be  con- 
trolled by  one  quick-opening  standard  radiator- valve  provided 
with  union  and  of  proper  size,  made  of  best  (steam  metal,  extra 
heavy,  with  composition  disk  or  )  [quick-opening  ]  to 
be  rough-body  plated  all  over  and  provided  with  wood  handle. 
All  radiators  shall  be  fitted  with  automatic  air-vents.  [Radiator 
return-connections  shall  be  made  with  body  ell 

unions.] 

When  indirect  radiators  are  to  be  controlled  same  shall  be 
fitted  with  iron  wheel-gate  valves. 

SYSTEM   OF  WARMING  AND   DISTRIBUTION  OF   RADIATION. 

The  building  specified  will  be  heated  by  means  of  ornamental 
direct,  prime  surface  indirect,  and  no  direct-indirect  radiation, 
located  in  the  several  rooms  to  the  best  advantage,  according 
as  conditions  of  building  and  will  of  owner  permit,  and  as 
shown  in  following  schedule.  Indicated  temperatures  to  be 
maintained  during  zero  weather. 


33 2  HEATING   AND    VENTILATING   BUILDINGS. 

SCHEDULE. 


Floor. 

Room. 

Square 
Feet 
Direct 

Square 
Feet 
Indirect 

Sq.  Ft. 
Direct- 
Indirect 

Height 
Radiation. 

Tempera- 
ture F. 

Radiation. 

Radiation. 

Radiation. 

First, 

N.  W. 

165 

70° 

S.W. 

.... 

150 

.... 

70° 

S.E. 

.... 

100 

.... 

65° 

W. 

50 

f  , 

20" 

70° 

s. 

24 

38'' 

70° 

Second. 

N.  W. 

52 

38" 

68* 

S.W. 

48 

38" 

68° 

S.E. 

48 

&Ql> 
OO 

68° 

W. 

36 

. 

24" 

68° 

S. 

20 

. 

38" 

65° 

Third. 

W. 

24 

38" 

65° 

S. 

16 

• 

38" 

65Q 

INDIRECT   RADIATION. 
(NOTE. — Omitted  on  specifications  when  heating  system  is  all  direct.) 

The  indirect  radiators  shall  consist  of  stacks  or  clusters  of 
prime  surfaces  connected  together  with  tight  joints,  and  firmly 
suspended  from  ceiling  by  suitable  wrought-iron  hangers,  as 
directed  by  radiator  makers,  or  by  other  methods  equally- 
good.  (There  shall  be  a  difference  of  level  of  not  less  than 
eighteen  inches  between  lowest  point  of  all  indirect  radiation  and 
the  water-line  of  boiler.) 

All  stacks  shall  be  so  piped  and  hung  as  to  permit  a  quick, 
noiseless,  and  constant  flow  throughout  of  (steam  and  all  water 
of  condensation)  [the  heated  water]. 

COLD-AIR   DUCTS,    CASINGS,    ETC. 
(NOTE. — Omitted  on  specifications  when  heating  system  is  all  direct.) 

The  area  of  internal  cross-section  of  fresh-air  inlet  and  duct, 
as  well  as  registers  and  warm-air  outlet,  shall  never  be  less 
than  standards  of  measurements  laid  down  in  Carpenter's 
"  Heating  and  Ventilating  Buildings."  Fresh-air  inlet  shall 
be  of  600  square  inches  area,  and  shall  be  provided  with 
substantial  iron  wire-gauze  screen.  Connecting  cold-air  duct 
and  casing  of  indirects  shall  be  made  of  galvanized  iron  (No. 
20  or  heavier),  provided  with  door  for  clean-out  and  inspection 
— all  joints  being  made  permanently  air-tight.  Cross-section 
of  duct  throughout  its  length  to  be  as  nearly  uniform,  circular 


SPECIFICATION  PROPOSALS— SUGGESTIONS.  333 

or  square,  as  conditions  of  building  permit.  Casing  of  indirects 
shall  be  so  erected  that  all  entering  air  must  pass  through  each 
stack,  and  be  warmed,  before  passing  to  its  respective  outlet 
register.  Stacks  shall  be  so  hung  and  encased  that  the  full  area 
of  inlet  and  outlet  ducts  shall  be  maintained  above  and  below 
the  stack,  which  space  shall  in  no  case  be  less  than  ten  inches 
in  height,  by  the  length  and  breadth  of  stack,  and  casing  shall 
be  so  arranged  that  all  inflowing  fresh  air  shall  be  heated  and 
conveyed  to  destination  without  loss  through  tin  warm-air 
ducts,  of  areas  as  above  provided  for,  same  to  be  furnished  by 
owner,  and  set  in  walls  or  floors  by  owner,  as  directed  by  ar- 
chitects. Each  cold-air  inlet  shall  be  provided  with  one  con- 
trolled damper,  fitted  with  iron  handle. 

REGISTERS   AND   REGISTER-BOXES. 
(NOTE. — Omitted  on  specifications  when  heating  system  is  all  direct.) 

All  registers  shall  be  of  Jones  design.  The  sum  of  areas  of 
openings  in  same  never  to  be  less  than  area  of  warm-air  outlet. 
Registers  to  be  set  flush  with,  and  firmly  fastened  in,  openings 
in  floor  or  wall  provided  by  owner,  and  to  be  located  to  best 
advantage  according  as  conditions  of  building  permit.  Proper 
register-boxes  made  of  /.  X.  tin  shall  be  provided  by  contractor 
for  reception  of  registers. 

CUTTING,    PAINTING,    BRONZING,    ETC. 

All  cutting  and  carpenter  work  shall  be  done  by  owner  as 
directed  by  contractor.  All  uncovered  exposed  piping  in  boiler- 
room  shall  receive  two  coats  of  best  or  drying  Japan  paint. 
All  exposed  piping  and  radiation  above  boiler-room  to  receive 
one  coat  of  priming  and  one  coat  of  pale-gold  bronze. 

EXTRAS. 

It  is  understood  and  agreed,  upon  the  acceptance  of  the 
Proposal  accompanying  this  Specification,  that  any  and  all 
verbal  or  other  agreements,  statements,  or  representations 
made  by  any  person  or  persons,  for  or  on  behalf  of  the  con- 
tractor, shall  be  considered  as  absolutely  merged  in  the  Pro- 


334  HEATING   AND    VENTILATING   BUILDINGS. 

posal  and  Specification,  and  that  the  contract  then  existing  shall 
be  taken  and  held  to  be  fully  set  forth  and  expressed  therein. 
If  any  deviation  in  system,  material,  or  mode  of  installation 
is  to  be  made,  such  change  shall  be  considered  an  "  extra,"  and 
must  be  provided  for  by  a  special  agreement. 

COMPLETION   AND   TESTING. 

If  this  Specification  with  accompanying  Proposal  be  accepted 
notice  of  date  when  work  may  begin  shall  be  given  contractor, 
and  same  shall  be  prosecuted  with  due  despatch,  and  shall  be 
completed  on  or  before  ,  whereupon  notice  to  that 

effect  shall  be  served  on  architect.  Should  any  unforeseen  or 
unavoidable  delay  occur,  same  shall  not  constitute  a  breach  of 
contract  on  the  part  of  contractor.  Upon  notification  that 
work  as  herein  provided  for  has  been  completed,  same  shall  be 
promptly  inspected,  and  "accepted"  or  "  rejected,"  and  notice 
thereof  served  on  the  contractor.  Acceptance  shall  in  no  event 
waive  the  guarantee  herein  below  given.  Failure  to  promptly 
inspect  and  accept  or  reject  work  shall  be  considered  as  accept- 
ance, and  shall  entitle  undersigned  to  payments  as  provided  for. 
"  Testing  "  shall  consist  of  firing  boiler  all  fuel  for  which  shall 
be  delivered  in  boiler-room,  and  furnished  by  owner,  and  the 
developing  of  a  (steam-pressure  not  exceeding  fifteen  pounds  to 
the  square  inch)  [flow-temperature  not  less  than  degrees 

Fahrenheit  without  boiling  over]  and  the  making  tight  of  all 
joints  in  system. 

Determination  of  fulfilment  of  guarantee  shall  be  gauged 
by  standards  set  down  in  Carpenter's  "  Heating  and  Ventilat- 
ing Buildings,"  page  86.  If  the  condition  of  building  is  such 
that  work  cannot  be  completed  without  delay,  and  that  delay 
requires  running  of  all  or  part  of  apparatus  for  use  or  con- 
venience of  any  one  other  than  the  contractor,  it  will  only  be 
so  run  at  the  risk  and  expense  of  owner,  and  apparatus  must 
be  delivered  again  in  as  good  condition  as  when  taken.  A 
payment  of  five  (5)  dollars  shall  be  due  for  each  radiator  dis- 
connected and  reconnected. 


SPECIFICATION  PROPOSALS— SUGGESTIONS.  335 

IN   GENERAL. 

Estimates  for  capacity  of  within  apparatus,  as  well  as  this 
Specification  and  accompanying  Proposal,  are  ail  based  on 
dimensions,  information,  etc.,  concerning  construction  of  build- 
ing furnished  by  architects;  and  if  such  dimensions,  information, 
etc.,  are  erroneous,  or  if  changes  shall  be  made  in  construction 
of  building,  then  in  so  far  as  such  deviations  detract  from  effi- 
ciency of  apparatus,  the  guarantee  as  to  the  efficiency  thereof 
which  is  herein  given  shall  be  deemed  cancelled.  Instructions 
as  to  conduct  of  work  must  be  made  to  the  contractor  and  not 
to  employees,  and  all  instructions  from  architects  shall  be  con- 
sidered as  final,  unless  otherwise  advised  by  owner. 

GUARANTEE. 

When  the  apparatus  as  herein  proposed  to  be  furnished  shall 
be  completed,  the  same  is  guaranteed  to  be  capable  of  warming 
the  rooms  entered  on  schedule,  to  the  temperatures  specified 
therein,  when  apparatus  is  run  as  directed,  and  under  the  con- 
ditions which  would  maintain  in  the  finished  building.  Any 
failure  to  fulfill  this  guarantee  by  reason  of  any  defect  of  work- 
manship, material,  or  efficiency  within  a  period  of  one  year  will 
be  made  good  by  contractor  within  a  reasonable  time  after 
receiving  notice  of  such  defect. 

N.  B.  The  term  "  defect "  as  above  used,  shall  not  be  con- 
strued to  cover  such  imperfections  as  result  from  accident,  de- 
sign, or  the  natural  wear  and  tear  of  use.  The  contractor  shall 
have  and  retain,  until  the  final  payment  in  full  shall  have  been 
made,  a  first  and  valid  lien  upon  all  materials  (including  pipe, 
fittings,  valves,  covering,  radiators,  registers,  ducts,  boilers,  etc.) 
furnished  by  contractor  under  terms  of  this  specification  and 
accompanying  proposal,  and  shall  have  the  right  at  all  times 
prior  to  such  final  payment,  upon  failure  on  part  of  owner,  to 
make  all  payments  as  provided  for,  to  take  possession  of  and 
remove  the  said  materials,  and  to  retain  the  possession  of  same 
and  every  part  thereof,  and  also  to  retain  all  payments  that 
have  been  made  on  account  thereof  as  liquidated  damages  for 
non-fulfilment  of  contract. 


336  HEATING   AND    VENTILATING   BUILDINGS. 

SPECIAL   NOTE. 

This  Specification  with  accompanying  Proposal  shall  be  ac- 
cepted or  rejected  on  or  before  inst.,  and  notice  thereof 
be  served  on  contractor. 

Respectfully  submitted, 

JOHN  G.  DOE  Co. 

October  i,  1895. 

173.  Form  of  Uniform  Contract.— 

UNIFORM  CONTRACT  FOR  THE  CONSTRUCTION  OF  HEAT- 
ING APPARATUS  (TO  BE)  ADOPTED  FOR  USE  BY  THE 
MASTER  STEAM  AND  HOT-WATER  FITTERS'  ASSOCIA- 
TION OF  THE  UNITED  STATES.* 

(Copyright,  1895,  by  the  Master  Steam  and  Hot-Water  Fitters'  Association  of  the 
United  States.) 

THIS  AGREEMENT,  made  and  concluded  at  Kalamazoo, 
State  of  Michigan,  the  first  day  of  January,  in  the  year  one 
thousand  eight  hundred  and  ninety-yfo^,  by  and  between  Jones 
&  Brown,  of  Chicago,  State  of  Illinois,  for  themselves  and  their 
legal  representatives,  parties  of  the  first  part  (hereinafter  desig- 
nated the  Contractor),  and  R.  /.  Peters,  of  Kalamazoo,  State 
of  Michigan,  for  himself  and  his  legal  representatives,  party  of 
the  second  part  (hereinafter  designated  the  Owner). 

WITNESSETH,  That  the  Contractor,  in  consideration  of 
the  fulfilment  of  the  agreements  herein  made  by  the  Owner, 
agrees  with  the  said  Owner,  as  follows: 

ARTICLE  I.  The  Contractor,  for  the  consideration  herein- 
after provided,  covenants  and  agrees,  with  the  Owner,  that  the 
Contractor  shall  and  will,  within  the  space  of  three  months 
next,  after  the  date  hereof,  in  a  good  and  workmanlike  manner, 
and  at  his  own  proper  charge  and  expense,  well  and  substantially 
build,  furnish,  and  erect  a  certain  Steam  Heating  Apparatus,  at 
444  4th  Avenue,  City  of  Kalamazoo,  according  to  the  Specifi- 
cations, Drawings,  and  Plans  designed  by  Thomas  Robinson, 
Architect,  which  Specifications,  Drawings,  and  Plans  are  made 
a  part  of  this  Contract  and  are  identified  by  the  signatures  of 
the  parties  hereto. 

*  Printed  words  in  italics  to  be  supplied  in  each  contract. 


SPECIFIC  A  riON  PROPOSA  LS—S  UGGES  TIONS.  337 

ARTICLE  II.  No  alterations  shall  be  made  in  the  work 
shown  or  described  by  the  drawings  and  specifications,  except 
upon  a  written  order  of  the  Architects,  and  when  so  made,  the 
value  of  the  work  added  or  omitted  shall  be  computed  by  the 
Architects,  and  the  amount  so  ascertained  shall  be  added  to  or 
deducted  from  the  contract  price.  In  the  case  of  dissent  from 
such  award  by  either  party  hereto,  the  valuation  of  the  work 
added  or  omitted  shall  be  referred  to  three  (3)  disinterested 
arbitrators,  one  to  be  appointed  by  each  of  the  parties  to  this 
Contract,  and  the  third  by  the  two  thus  chosen  ;  the  decision 
of  any  two  of  whom  shall  be  final  and  binding,  and  each  of  the 
parties  hereto  shall  pay  one-half  of  the  expenses  of  such  ref- 
erence. 

ARTICLE  III.  Should  any  difference  arise  in  interpreting 
the  Plans  or  Specifications,  involving  or  assuming  additional 
compensation,  the  Contractor  shall,  upon  written  notice  from 
the  Owner,  immediately  execute  such  interpretation,  the  ques- 
tion of  compensation  to  be  determined  on  completion  by 
arbitrators,  as  provided  in  Article  II. 

ARTICLE  IV.  All  of  the  materials  and  workmanship  of  the 
apparatus  to  be  of  the  quality  as  expressed  in  said  Specifica- 
tions, Drawings,  and  Plans ;  said  Owner  to  reserve  the  right  to 
reject,  through  himself  or  his  authorized  agent,  all  material  or 
workmanship  of  an  inferior  quality,  which  said  Contractor  may 
attempt  to  use  in  the  erection  of  said  Heating  Apparatus,  and 
if  the  said  Contractor,  after  being  notified,  neglects  or  refuses 
to  do  the  work,  or  furnish  the  materials  as  called  for  in  the 
Specifications,  Drawings,  and  Plans,  then,  acd  in  that  case,  said 
Owner  shall  give  notice  in  writing  to  the  Contractor,  which 
notice  is  to  set  forth  in  full  the  cause  or  causes  of  complaint. 
If  the  Contractor  demurs  and  refuses  to  do  the  work  or  furnish 
the  materials  as  directed  in  the  notice  of  complaint,  within 
three  days  from  the  date  of  said  notice,  resort  to  arbitration 
shall  be  had  as  provided  in  Article  II. 

ARTICLE  V.  The  Owner  shall  not,  in  any  manner,  be 
answerable  or  accountable  for  any  loss  or  damage  that  shall  or 
may  happen  to  the  said  works,  or  any  parts  thereof  respectively, 
or  for  any  of  the  materials  or  other  things  used  and  employed 
in  finishing  and  completing  the  same,  loss  or  damage  by  fire 


HEATING   AND    VENTILATING   BUILDINGS. 

excepted.  The  Contractor  shall  be  responsible  for  all  damage 
to  the  building  and  adjoining  premises,  and  to  individuals, 
caused  by  himself  or  his  employees  in  the  course  of  their 
employment. 

ARTICLE  VI.  It  is  hereby  mutually  agreed  between  the 
parties  hereto,  that  the  sum  to  be  paid  by  the  Owner  to  the 
Contractor  for  said  work  and  materials  shall  be  Seven  Thousand 
Dollars  ($7,000),  subject  to  additions  and  deductions  as  herein- 
before provided,  and  that  such  sum  shall  be  paid  in  current 
funds  by  the  Owner  to  the  Contractor,  in  monthly  payments, 
to  the  amount  of  oo  per  cent  of  the  value  of  materials  delivered 
to  and  labor  performed  in  the  said  building  during  the  preced- 
ing month ;  and  the  remaining  10  per  cent  shall  be  paid  as  a 
final  payment  within  30  days  after  this  contract  is  fulfilled. 

All  payments  shall  be  made  upon  written  certificates  of  the 
Architects  to  the  effect  that  such  payments  have  become  due. 

ARTICLE  VII.  It  is  mutually  agreed  that  payments  for  all 
additional  work  shall  be  made  at  the  same  time  and  in  the 
same  manner  as  contract  payments,  Article  VI. 

ARTICLE  VIII.  It  is  mutually  agreed  that  should  default 
be  made  in  any  of  the  payments  as  herein  provided,  the  Con- 
tractor shall  have  the  right  to  stop  work  and  withdraw  all  un- 
used materials  until  such  payment  is  properly  made,  or  may  at 
his  option  cancel  the  contract. 

ARTICLE  IX.  It  is  further  mutually  agreed  that  the  essence 
of  this  Agreement  is  that  the  Owner  purchasing  this  apparatus 
and  paying  therefor  will  receive  full  value  to  the  extent  that 
it  will  warm  the  subdivisions  of  the  building  indicated  on  the 
plans  to  70  degrees  Fahrenheit  in  the  coldest  weather ;  but 
nothing  herein  contained,  or  in  the  Specification  accompanying 
the  same,  shall  prevent  the  Contractor  from  receiving  from  the 
Owner  a  final  payment  for  the  work  herein  and  at  the  time 
stipulated. 

ARTICLE  X.  The  Contractor  guarantees  his  workmanship 
and  materials,  the  capacity  of  the  boiler,  the  circulation  of  the 
system  and  the  efficiency  of  the  heating  surfaces,  all  as  called 
for  in  the  Specifications  hereto  attached,  and  should  any  de- 
fects or  deficiencies  occur,  other  than  from  neglect  on  the  part 
of  the  Owner  or  his  employees,  within  the  term  of  one  year 


SPECIFIC  A  TION  PROPOSA  LS—S  UG  GESTIONS.  3  39- 

from  the  above  date,  the  Contractor  agrees  to  make  good  the 
same  upon  a  written  notice  from  the  Owner  at  the  Contractor's 
expense. 

ARTICLE  XI.  If  at  any  time  there  shall  be  evidence  of  any 
lien  or  claim  for  which,  if  established,  the  Owner  of  the  said 
premises  might  become  liable,  and  which  is  chargeable  to  the 
Contractor,  the  Owner  shall  have  the  right  to  retain  out  of  any 
payment  then  due,  or  thereafter  to  become  due,  an  amount 
sufficient  to  completely  indemnify  himself  against  such  lien  or 
claim.  Should  there  prove  to  be  any  such  claim  after  all  pay- 
ments are  made,  the  Contractor  shall  refund  to  the  Owner  all 
moneys  that  the  latter  may  be  compelled  to  pay  in  discharging 
any  lien  on  said  premises  made  obligatory  in  consequence  of 
the  Contractor's  default. 

ARTICLE  XII.  It  is  further  mutually  agreed,  between  the 
parties  hereto,  that  no  certificate  given  or  payment  made  under 
this  Contract,  except  the  final  certificate  or  final  payment,  shall 
be  conclusive  evidence  of  the  performance  of  this  Contract, 
either  wholly  or  in  part,  and  that  no  partial  payment  shall  be 
construed  to  be  an  acceptance  of  defective  work  or  improper 
materials. 

ARTICLE  XIII.  The  said  parties  for  themselves,  their 
heirs,  executors,  administrators,  and  assigns,  do  hereby  agree 
to  the  full  performance  of  the  covenants  herein  contained. 

IN  WITNESS  WHEREOF,  the  parties  to  these  presents 
have  hereunto  set  their  hands  and  seals,  the  day  and  year  first 
above  written. 

In  presence  of 

/.  B.  Sax* 

Jones  &  Brown  (SEAL) 

R.  J.  Peters  (SEAL) 

(SEAL) 
(SEAL) 

ALTERNATE   FOR   ARTICLE  VI. 

It  is  hereby  mutually  agreed,  between  the  parties  hereto,  that 
the  sum  to  be  paid  by  the  Owner  to  the  Contractor  for  said  work 
and  materials  shall  be  Seven  Thousand  Dollars  ($7.000}  sub- 
ject to  additions  and  deductions  as  hereinbefore  provided,  and 


340  HEATING   AND    VENTILATING   BUILDINGS. 

that  such  sum  shall  be  paid  in  current  funds  by  the  Owner  to 
the  Contractor  in  instalments,  as  follows : 

When  The  Boilers  are  delivered  and  set,         $1,500 

When  Steam  Mains  and  Risers  are  in  place,  $1.500 

When  The  Radiators  are  delivered,                 $1,500 

When  The  Radiators  are  connected,                  $1,500 

And  the  balance  of  $ 1,000  as  a  final  payment  to  be  made 
within  30  days  after  this  contract  is  fulfilled. 

All  payments  shall  be  made  upon  written  certificates  of  the 
Architects  to  the  effect  that  such  payments  have  become  due. 

174.  Specifica.tions  for  Plain  Tubular  and  Water-tube 
Boilers. — This  boiler  is  employed  extensively  for  heating  large 
buildings.  The  boiler  is  described  on  page  130,  and  several 
methods  of  setting  are  shown  on  page  145.  The  following 
specifications  represent  the  best  practice  of  to-day  in  the  con- 
struction of  plain  tubular  boilers  employed  for  heating.  They 
are  in  each  case  to  be  set  in  brickwork,  substantially  as  de- 
scribed on  page  143. 


SPECIFICA  TION  PROPOSALS— SUGGESTIONS. 


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342  HEATING   AND    VENTILATING   BUILDINGS. 

Riveting  for  a  Working  Pressure  of  100  Ibs. — Horizontal  seams  double- 
staggered  riveted,  lap-joint ;  pitch  of  rivets  3"  longitudinally  and  T.\" 
diagonally.  Circular  seams  single-riveted,  lap-joint ;  pitch  of  rivets  2%". 
Flange  seam  and  vertical  seam  of  dome  double-staggered  riveted ; 
pitch  of  rivets  3"  longitudinally  and  2j"  diagonally.  Circular  seam  at 
dome  head  single-riveted  ;  pitch  of  rivets  2^-". 

For  a  Working  Pressure  of  125  Ibs. — Horizontal  seams  triple-riveted  ; 
lap-joints  required  except  for  boilers  exceeding  66"  diameter,  when  hori- 
zontal seams  shall  be  made  with  butt-joint,  with  inside  and  outside  lap 
strips  covering  the  joint,  these  strips  same  thickness  as  plate  in  shell  of 
boilers  ;  three  rows  of  rivets  each  side  of  joint;  pitch  of  rivets  on  triple 
lap-joints  3^"  longitudinally,  2"  diagonally,  2-f''  transversely.  Pitch  of 
rivets  on  butt- strapped  joints  3^"  and  6£"  longitudinally,  2"  diagonally, 
and  2-f"  transversely.  Circular  seams  single-riveting,  lap-joint;  pitch 
of  rivets  i\" .  Flange  seam,  od,  dome  triple-riveting  staggered ;  pitch 
of  rivets  3"  longitudinally  and  2"  diagonally  ;  vertical  seam  of  dome 
double-staggered  riveting ;  pitch  of  rivets  3"  longitudinally  and  2\" 
diagonally.  Circular  seam  at  dome  head  single-riveting ;  pitch  of 
rivets  2j". 

Bracing. — All  braces  to  have  a  sectional  area  of  \\  square  inches  and 
to  be  of  the  solid  crowfoot  style,  and  riveted  to  heads  and  shell  with  two 
rivets  in  each  end  ;  pitch  of  rivets  4".  On  heads  of  boiler  these  braces 
to  be  set  radially  and  spaced  about  7"  centres,  and  to  lead  from  head  to 
shell  and  to  be  at  least  3  ft.  in  length  and  preferably  longer.  Braces  in 
dome  to  lead  from  shell  of  dome  to  shell  of  boiler,  spaced  about  18" 
centres,  two  rivets  in  each  end  spaced  4"  centres  ;  braces  as  long  as 
height  of  dome  will  permit.  Head  of  dome  may  be  convex  and  without 
braces. 

Tube  Setting. — Tubes  to  be  set  in  straight  horizontal  and  vertical 
rows,  one  inch  apart  each  way,  and  no  tube  nearer  shell  than  three 
inches.  Distance  from  top  of  upper  row  of  tubes  to  shell  not  less  than 
one  third  the  diameter  of  boiler.  Tubes  to  extend  through  heads,  and 
be  carefully  expanded  and  beaded  to  the  heads. 

Calking. — Calking  edges  of  each  seam  to  be  bevelled  by  machine  be- 
fore plates  are  put  together,  and  calking  tool  driven  straight. 

Manholes. — A  suitable  manhole  in  top  of  shell,  having  an  internal 
opening  ii"xi5",  reinforced  with  strong  internal  frame  of  forged  iron. 
Manhole  to  be  provided  with  suitable  plate,  bolt,  guard,  and  gasket.  For 
large  boilers  a  manhole  shall  be  left  in  front  head  beneath  the  tubes. 

Hand-holes. — A  suitable  hand-hole,  4^"  x  6",  in  each  head  under  tubes, 
provided  with  suitable  plate,  bolt,  guard,  and  gasket. 

Outlets. — Outlet  for  steam  should  be  on  top  of  the  dome,  the  opening 
into  dome  to  be  reinforced  with  wrought-iron  flange  properly  threaded 
and  riveted  to  the  head  ;  the  safety-valve  to  be  attached  to  this  opening. 

The  opening  for  blow-off  should  be  in  the  back  head  at  the  side  of 
hand-hole.  The  opening  for  surface  blow  shall  be  in  the  top  of  the  shell, 


SPECIFICATION  PROPOSALS— SUGGESTIONS.  343 

and  provided  with  pipe  having  a  trumpet  shaped  mouth  ending  at  water- 
line. 

The  opening  for  feed  connection  should  be  in  the  top  of  shell  and 
reinforced.  The  feed-pipe  is  to  be  extended  downward  below  the  water- 
line,  and  at  least  four  feet  horizontally. 

The  upper  connection  for  water-column  should  be  in  front  head  near 
top.  The  lower  connection  for  water-column  should  be  in  front  head, 
about  on  the  centre  line  of  the  boiler. 

Wall-brackets. — There  should  be  two  heavy  cast-iron  wall -brackets 
riveted  to  each  side  of  shell  for  supporting  boiler  on  masonry.  These 
brackets  should  be  at  least  9  inches  wide  with  foot  12  inches  long,  and 
14  inches  on  the  boiler  and  \\  inches  thick,  with  heavy  rib  through  the 
centre.  These,  and  all  other  castings  riveted  to  the  shell,  to  conform  to 
the  shape  of  same  and  fit  accurately  without  linings  of  any  kind. 

Testing. — For  a  working  pressure  of  100  Ibs.'  the  boiler  should  be 
tested  to  a  hydrostatic  pressure  of  150  Ibs.  per  square  inch,  and  for  a 
working  pressure  of  125  Ibs.  it  should  be  tested  to  a  hydrostatic  pressure 
of  200  Ibs.  per  square  inch,  and  should  be  perfectly  tight  under  each  test. 

Castings. — The  boiler  should  be  provided  with  a  cast-iron  front  at 
least  £ '  thick,  with  double  flue,  fire  and  ash-pit  doors  swinging  right  and 
left.  Fire-doors  should  be  provided  with  perforated  liners  and  air-reg- 
isters. Provide  heavy  cast-iron  dead-plate,  arch-plate  over  fire-door,  and 
cast-iron  plates  at  each  side  of  fire-door  opening,  to  protect  the  fire-brick- 

The  grates*  should  equal  in  width  the  full  diameter  of  the  boiler,  and 
should  be  in  two  lengths,  with  necessary  bearing  bars  ;  the  entire  length 
of  the  grate  surface  should  equal  about  one  third  the  length  of  the  tubes. 

The  air-space  in  the  grates  for  soft  coal  should  be  from  £"  to  £",  and 
for  hard  coal  from  §'  'to  £''. 

Two  heavy  cast-iron  arch  bars  for  supporting  brick  at  rear  of  boiler. 

One  back  door  and  frame  of  cast  iron,  to  provide  access  to  rear  of 
the  setting. 

All  necessary  anchor-bolts  for  holding  front  and  back  doors  in  posi- 
tion, and  at  least  four  long  tie-bolts  extending  full  length  of  the  setting( 
with  cast-iron  washers  for  rear  end. 

Four  heavy  cast-iron  buck-stays  with  rods,  extending  crosswise  of  the 
setting,  for  supporting  side  walls. 

Four  cast-iron  wall-plates  with  rollers  for  supporting  brackets  to  rest 
upon. 

Fittings. — One  steam-gauge  inches  diameter.  One  lever  safety- 
valve.  One  water-gauge  fitted  to  cast-iron  water-column,  with  three 
gauge-cocks.  One  steam-cock  for  blow-off.  One  globe-valve,  and  one 
check-valve  for  feed-pipe  connections.  One  set  of  fire  tools,  slice- 
bar,  and  rake.  One  damper  with,  suitable  handles  and  with  auto- 
matic regulator. 

*  If  rocking  gates  are  desired,  name  of  manufacturer  should  be  specified. 


344  HEATING   AND    VENTILATING   BUILDINGS 

' 

It  is  generally  desirable  to  provide  two  independent  methods 
of  feeding,  so  that  an  accident  will  not  affect  the  supply  of  feed- 
water  ,  but  specifications  for  the  feed-pumps  are  not  often  in- 
cluded with  those  for  the  boiler. 

175.  Protection  from  Fire — Hot  Air  and  Steam  Heating. 
—Where  hot-air  stacks  or  steam-pipes  pass  up  through  parti- 
tions near  woodwork  there  is  considerable  danger  of  fire,  and 
for  this  reason  certain  requirements  have  been  made  both  as 
to  the  position  of  hot-air  pipes  in  furnace-heating  and  steam 
pipes  in  steam-heating.  The  following  digest,  compiled  by 
H.  A.  Phillips,  of  the  municipal  laws  relating  to  hot  pipes  in 
buildings,  in  force  in  some  of  the  principal  cities  of  the  United 
States,  appeared  in  the  American  Architect  and  Building  News, 
Feb.  1893,  and  is  useful  in  preparing  specifications.  They  are 
as  follows  : 

Boston. — i.  Hot-air  pipes  shall  be  at  least  i  inch  from  woodwork. 

(This  may  be  modified  by  inspector  in  first-class  buildings.) 

2.  Any  metal  pipe  conveying  heated  air  or  steam  shall  be  kept  i  inch 
from  any  woodwork,  unless  pipe  is  protected  by  soapstone  or  earthen 
tube  or  ring,  or  metal  casing, 

Baltimore. — i.  Metal  flue  for  hot  air  may  be  of  one  thickness  of 
metal,  if  built  into  stone  or  brick  wall. 

2.  Otherwise  it  must  be  double,  the  two  pipes  separated  by  i  inch 
air-space. 

3.  No  woodwork  shall  be  placed  against  any  flue  or  metal  pipe  used 
for  conveying  hot  air. 

Chicago.  —  i.  Hot-air  conductors  placed  within  10  inches  of  wood- 
work shall  be  made  double,  one  within  the  other,  with  at  least  •£  inch 
air-space  between  the  two. 

2.  All  hot-air  flues  and  appendages  shall  be  made  of  1C  or  IX  bright 
tin. 

3.  Steam-pipes  shall  be  kept  at  least  2  inches  from  woodwork,  unless 
protected  by  soapstone,  earthen  ring  or  tube,  or  rest  on  iron  supports. 

Cincinnati. — No  pipes  conveying  heated  air  or  steam  shall  be  placed 
nearer  than  6  inches  to  any  unprotected  combustible  material.  All 
subject  to  approval  of  inspector. 

Cleveland. — i.  Hot-air  conductors  placed  within  10  inches  of  wood- 
work shall  be  .made  double,  one  within  the  other,  with  at  least  |  inch 
air-space  between  the  two. 

2,  No  pipes  conveying  heated  air  or  steam  shall  be  placed  nearer 
than  6  inches  to  any  unprotected  combustible  material. 

Denver.— Metal  flue  for  hot  air  may  be  of  one  thickness  of  metal,  if 


SPECIFICATION  PROPOSALS— SUGGESTIONS.  345 

built  into  stone  or  brick  wall ;  otherwise  it  shall  be  made  double  or 
wrapped  in  incombustible  material. 

Detroit. — No  metal  pipe  for  conveying  hot  air  shall  be  placed  nearer 
than  3  inches  to  any  woodwork.  Such  pipes  over  15  feet  long  shall  be 
safely  stayed  by  wire  or  metal  rods. 

District  of  Columbia. — i.  Hot-air  pipes  shall  be  at  least  i  inch  from 
woodwork. 

2.  Pipes  passing  through  stud  or  wooden  partitions  shall  be  guarded 
by  double  collar  of  metal,  "giving  at  least  2  inches  air-space,  having 
holes  for  ventilation,  or  other  device  equally  secure, "to  be  approved  by 
inspector." 

3.  Metal  pipe  double,  with  the  space  filled  with  i  inch  of  non-com- 
bustible, non-conducting  material,  or  a  single  pipe  surrounded  by  i  inch 
of  plaster  of  Paris  or  other  non-conducting  material  between  pipe  and 
timber. 

Kansas  City.—i.  Any  metal  pipe  conveying  heated  air  or  steam  shall 
be  kept  i  inch  from  any  woodwork,  unless  pipe  is  protected  by  soap- 
stone  or  earthen  tube  or  ring,  or  metal  casing,  or  otherwise  protected  to 
satisfaction  of  superintendent. 

2.  No  wooden  flue  or  air-duct  for  heating  or  ventilation  shall  be 
placed  in  any  building. 

Memphis. — i.  All  stone  or  brick  hot-air 'flues  and  shafts  shall  be 
lined  with  tin  pipes. 

2.  No  wooden  casing,  furring,  or  lath  shall  be  placed  against  or  over 
any  smoke-flue  or  metal  pipe  used  to  convey  hot  air  or  steam. 

3.  No  metal  flues  or  pipes  to  convey  heated  air  shall  be  allowed 
unless  inclosed  with  4  inches  thickness  of  hard,  incombustible  material, 
except  horizontal  pipes  in  stud  partitions,  which  shall  be  built  in  the 
following  manner:  The  pipes  shall  be  double,  one  inside  the  other,  and 
£  inch  apart,  and  with  3  inches  space  between  pipe  and  stud  on  each 
side;  the  inside  faces  of  said  stud  well  lined  with  tin  plate,  and  the  out- 
side face  with  iron  lath  or  slate.     Where  hot-air  pipe  passes  through 
partition  shall  be  at  least  8  feet  from  furnace. 

4.  Horizontal  hot-air  pipes  shall  be  kept  6  inches  below  floor-beams 
or  ceiling.     If  floor-beams  or  ceiling  are  plastered  or  protected  by  metal 
shield,  then  distance  shall  not  be  less  than  3  inches. 

5.  Where  hot-air  pipes  pass  through  wooden  or  stud  partition,  they 
shall  be  guarded  by  double  collar  of  metal  with  2-inch  air-space  and 
holes  for  ventilation,  or  by  4  inches  of  brickwork. 

6.  No  hot-air  flues  or  pipes  shall  be  allowed  between  any  combus- 
tible floor  or  ceiling. 

7.  Steam- pipe  shall  not  be  placed  less  than  2  inches  from  woodwork 
unless  wood  is  protected  by  metal  shield,  and  then  distance  shall  not  be 
less  than  i  inch. 

8.  Steam-pipes  passing  through  floors  and  ceilings  or  lath-and-plaster 


UNIVERSITY  J 


34-6  HEATING   AND    VENTILATING   BUILDINGS. 

partitions  shall  be  protected  by  metal  tube  2  inches  larger  in  diameter 
than  pipe. 

9.  Wooden  boxes  or  casings  inclosing  steam-pipes  and  all  covers  to 
recesses  shall  be  lined  with  iron  or  tin  plate. 

Milwaukee. — i.  Hot-air  conductors  placed  within  10  inches  of  wood- 
work shall  be  made  double,  one  within  the  other,  with  at  least  i  inch 
air-space  between  them. 

2.  All  hot-air  flues  and  appendages  shall  be  made  of  1C  or  IX  bright 
tin. 

Nashville. — I.  Sheet-iron  flue  running  through  floor  or  roof  shall 
have  a  sheet-iron  or  terra-cotta  guard  at  least  2  inches  larger  than  flue. 

2.  Steam-pipes  shall  be  kept  at  least  2  inches  from  woodwork. 

3.  All  steam  and  hot-air  flues  and  pipes  must  be  suspended  by  iron 
brackets. 

Newark. — i.  Hot-air  pipes  shall  be  set  at  least  2  inches  from  wood- 
work and  the  woodwork  protected  with  tin. 

2.  Such  pipes  placed  in  lath-and-plaster  partitions  must  be  covered 
with  iron,  tin,  or  other  fire-proof  material. 

New  York. — (Same  regulations  as  noted  under  heading  of  "  Mem- 
phis.") 

No  hot-air  flue  or  pipe  allowed  between  combustible  floor  or  ceiling. 

Omaha. — i.  Steam-pipe  shall  not  be  placed  less  than  2  inches  from 
woodwork  unless  wood  is  protected  by  metal  shield  ;  and  then  distance 
shall  not  be  less  than  i  inch. 

2.  Steam-pipes    passing  through  floors   and   ceilings,   or  lath-and- 
plaster  partitions,  shall  be  protected  by  metal  tube  2  inches  larger  in 
diameter  than  pipe. 

3.  Wooden  boxes  or  casings  inclosing  steam-pipes  and  all  covers  to 
recesses  shall  be  lined  with  iron  or  tin  plate. 

4.  Stud  partitions  in  which  hot-air  pipes  are  placed  to  be  at  least  5 
inches  wide,  and  the  space  between  studs  at  least  14  inches. 

5.  Hot-air  pipes  shall  not  be  placed  between  floor-joists  unless  same 
are  doubled  and  the  joists  14  inches  apart. 

6.  Bright  tin  shall  be  used  in  construction  of  all  hot-air  flues  and 
appendages. 

Providence. — i.  Hot-air  pipes  shall  be  at  least  i  inch  from  wood- 
work, unless  protected  by  soapstone  or  earthen  ring,  or  metal  casing 
permitting  circulation  of  air  around  pipe. 

2.  Steam-pipes  must  be  kept  at  least  i  inch  from  woodwork,  or  sup- 
ported by  incombustible  tubes  or  rest  on  iron  supports. 

St.  Louis. — i.  Hot-air  pipes  shall  be  at  least  i  inch  from  woodwork, 
unless  protected  by  soapstone  or  earthen  ring  or  metal  casing  permitting 
circulation  of  air  around  pipe. 

2.  Steam  or  hot-water  pipes  carried  through  wooden  partition  or 
between  joists,  or  in  other  close  proximity  to  woodwork,  shall  be 


SPECIFIC  A  TION  PROPOSALS— SUGGESTIONS.  347 

inclosed  in  clay  pipe  or  covered  with  felting  or  other  non-conducting 
material. 

San  Francisco. — i.  Metal  flue  for  hot  air  may  be  of  one  thickness  of 
metal,  if  built  into  stone  or  brick  wall;  otherwise  double,  one  pipe 
within  the  other,  i  inch  apart,  and  space  filled  with  fire-proof  material. 

2.  No  woodwork  shall  be  placed  against  any  flue  or  metal  pipe  used 
for  conveying  hot  air. 

3.  Steam-pipes  shall  be  placed  at  least  3  inches  from  woodwork,  or 
protected  by  ring  of  soapstone  or  earthenware. 

Wilmington. — Metal  pipes  to  carry  hot  air  shall  be  double,  one  inside 
the  other,  £  inch  apart ;  or,  if  single,  have  a  thickness  of  2  inches  of 
plaster  of  Paris  between  pipe  and  woodwork  adjoining  same. 

176.  Duty  of  the  Architect. — The  heating  system  is  a» 
essential  part  of  the  building  in  this  latitude,  and  it  should  be 
the  duty  of  the  architect  to  provide  building  designs  of  such 
character  that  it  can  be  readily  and  economically  installed.    The 
architect's  specifications  for  the  buildings  hould  provide  for  the 
construction  of  ventilating,  heating,  and  smoke  flues,  and  his 
plans  should  show  the  location,  including  pipe-lines,  of   every 
essential  part  of  the  heating  apparatus.     All  responsibility  re- 
garding flues  and  the  general  adaptability  of  the  heating  sys- 
tem to  the  building  should  be  assumed  by  the  architect,  and 
not  shifted  to  the  contractor.     If  the  heating  system  is  designed 
at  the  same  time  as  the  building,  slight  changes  can  be  made 
in  arrangements  of  details,  partitions,  doors,  etc.,  that  will  tend 
to  cheapen  construction,  and  will  add  to  the  efficiency  of  opera- 
tion and  the  general  appearance  of  the  heating  apparatus.     If 
steam  or  water  pipes  are  required  to  be  erected  out  of  sight, 
conduits   should    be    provided,   so   that  they  will   be    readily 
accessible  for  inspection  and  repairs. 

177.  Methods  of  Estimating  Cost  of  Construction. — In 
estimating  the  cost  of  construction  of  any  system  of  heating 
apparatus   the  contractor  must  depend  largely  upon  his  own 
experience  and  knowledge.    No  general  directions  can  be  given, 
but  a  few  suggestions  are  offered  which  may  aid  in  adopting  a 
systematic  method  of  proceeding.     Determine  first  the  amount 
and  character  of  radiation  to  be  placed  in  each  room  by  the 
methods  which  have  already  been  given  fully  in  Chapter  X. 
Second,  determine  the  position  and  sizes  of  pipes  leading  from 


HEATING   AND    VENTILATING   BUILDINGS. 

the  heater  to  the  various  radiating  surfaces  by  methods  given 
in  Chapter  XL 

To  facilitate  the  above  work,  a  set  of  floor  drawings  of  each 
story  should  be  obtained,  and  on  these  there  should  be  carefully 
laid  out  the  position  of  all  radiators,  flues,  pipe-lines,  etc.  After 
determining  the  amount  required,  a  schedule  of  material  should 
be  made  and  the  cost  should  be  computed. 

The  manufacturers  have  adopted  a  price,  which  is  changed 
very  rarely,  for  all  standard  fittings,  pipes,  etc.,  and  from  which 
a  discount  is  given  which  varies  with  the  condition  of  the 
market,  cost  of  material,  labor,  etc.  The  discount  is  usually 
large  upon  cast-iron  fittings  and  brass  goods,  being  seldom  less 
than  70  per  cent,  and  sometimes  80  per  cent  and  even  greater. 
The  discount  on  piping,  especially  the  smaller  sizes,  is  much 
less,  ordinarily  ranging  from  40  to  70  per  cent. 

The  cost  of  labor  will  vary  greatly  in  different  localities,  so 
that  no  general  method  of  estimating  can  be  given.  It  must 
be  determined  largely  by  experience  in  each  locality  and  with  j 
a  given  set  of  men.  The  cost  of  heaters  of  any  given  type,  with 
fittings,  etc.,  can  only  be  determined  accurately  by  correspond- 
ence with  manufacturers. 

Table  XXII  may  frequently  be  useful,  as  it  gives  the  list-  j 
price  of  the  principal  standard  fittings,  pipes,  and  valves  (seel 
appendix  to  book). 

178.  Suggestions  for   Pipe-fitting. — Certain  suggestions  I 
are  here  made  relating  to  the  actual  work  of  pipe-construction 
which  may  be  useful  to  those  not  having  an  extended  experi- 
ence. 

In  the  actual  construction  of  steam-heating  or  hot-water] 
heating  systems  it  is  usually  customary  to  send  a  supply  of! 
pipe  and  fittings  to  the  building  somewhat  greater  than  is 
required,  and  the  workman,  after  receiving  plans  of  construction 
which  show  the  location  and  sizes  of  the  various  pipes  to  be  ; 
erected,  makes  his  own  measurements,  cuts  the  pipes  to  the  i 
proper  length  in  the  building,  threads  them,  and  proceeds  tol 
screw  them  into  place.  In  some  rare  instances  all  lengths  of  j 
pipe  are  purchased  the  proper  length,  and  the  workman  has  j 
merely  to  put  them  in  the  proper  position.  The  skill  required  j 
for  pipe-fitting  may  seem  to  the  novice  to  be  easily  acquired  :  ] 


SPECIFICATION  PROPOSALS-^SUGGESl^IONS.  349 

this  is  not  true,  as  it  is  a  trade  requiring  as  much  training  and 
experience  as  any  with  which  the  writer  is  familiar. 

The  tools  belonging  to  this  trade  consist  of  tongs  or  wrenches 
for  screwing  the  pipe  together,  cutters  for  cutting,  taps  and  dies 
for  threading  the  pipe,  and  vises  for  holding  it  in  position  while 
cutting  or  threading.  A  very  great  variety  of  tongs  and 
wrenches  is  to  be  found  on  the  market,  some  of  which  are  ad- 
justable to  various  sizes  of  pipe,  and  others  are  suited  for  only 
one  size.  For  rapid  work  no  tool  is  perhaps  superior  to  the 
plain  tongs,  and  one  or  more  sets  especially  for  the  smaller  sizes 
of  pipes  should  always  be  available.  For  large  pipes,  chain 
tongs  of  some  pattern  will  be  found  strong  and  convenient,  and 
can  be  used  with  little  danger  of  crushing  the  pipe.  A  form  of 
adjustable  wrench  known  from  the  inventor  as  the  Stilson 
wrench  has  proved  a  very  excellent  and  durable  tool,  and  is 
well  worthy  a  place  in  the  chest  of  any  fitter.  Other  wrenches 
of  value  are  also  on  the  market,  one  with  a  triangular  head  and 
projecting  teeth  being  especially  valuable  for  small  pipes.  The 
wrenches  or  tongs  which  are  used  for  turning  the  pipe  in  most 
cases  exert  more  or  less  lateral  pressure,  and  if  too  great  strength 
is  applied  at  the  handles  there  is  a  tendency  to  split  the  pipe. 
It  is  an  advantage  to  have  the  tongs  or  wrenches  catch  on  the 
outer  circumference  of  the  pipe  with  as  little  lateral  pressure 
as  posible,  and  to  this  end  the  projecting  edges  should  be  kept 
sharp  and  clean. 

The  cutter  ordinarily  employed  for  small  pipe  consists  of 
one  or  more  sharp-edged  steel  wheels,  which  are  held  in  an  ad- 
justable frame,  the  cutting  being  performed  by  applying  pres- 
sure and  revolving  it  around  the  pipe.  With  this  instrument 
the  cutting  is  accomplished  by  simply  crowding  the  metal  to  one 
side,  and  hence  burrs  of  considerable  magnitude  will  be  formed 
both  on  the  outside  and  inside  of  the  pipe.  The  outside  burr 
must  usually  be  removed  by  filing  before  the  pipe  can  be 
threaded.  The  inside  burr  forms  a  great  obstruction  to  the 
flow  of  steam  or  water,  and  should  in  every  case  be  removed  by 
the  use  of  a  reamer.  Workmen  quite  often  neglect  to  remove 
the  inside  burr.  A  cutter  consisting  of  a  cape  chisel  set  in  a 
frame  is  more  difficult  to  use  and  keep  in  order,  although  it 
makes  cleaner  cuts ;  it  can  be  had  in  connection  with  some 


350  HEATING   AND    VENTILATING   BUILDINGS. 

of  the  adjustable  die-stocks,  but  is  rarely  used.  Pipes,  es- 
pecially the  larger  sizes,  are  sometimes  cut  by  expert  workmen 
with  diamond-pointed  or  cape  chisels,  but  this  process  requires 
too  much  time  to  be  applicable  to  small  pipes. 

The  hack-saw  is  coming  into  use  to  some  extent  for  cutting 
pipes,  and  is  an  excellent  instrument  for  this  purpose,  as  it  does 
not  tend  to  burr  or  crush  the  pipe,  and  is  quite  as  rapid  as  the 
wheel-cutter. 

The  dies  for  threading  the  pipes  are  of  a  solid  form,  each 
die  fitting  into  a  stock  or  holder  with  handles,  or  of  an  adjust- 
able form,  the  dies  being  made  of  chasers,  which  are  held  where 
wanted  and  can  be  set  in  various  positions  by  a  cam.  The 
adjustable  dies  can  be  run  over  the  pipes  several  times,  and 
hence  work  easier  than  solid  ones  ;  but  in  their  use  great  care 
should  be  taken  that  the  exterior  diameter  of  the  pipe  is  not 
made  less  than  the  standard  size.  The  cutting  edges  of  the 
dies  should  be  kept  very  sharp  and  clean,  otherwise  perfect 
threads  cannot  be  cut.  In  the  use  of  the  dies  some  lubricant, 
as  oil  or  grease,  kept  on  the  iron  will  be  found  to  add  materi- 
ally to  the  ease  with  which  the  work  can  be  done,  and  will  tend 
to  prevent  heating  and  crumbling  of  the  pipe  and  injury  to  the 
threads. 

Taps  are  required  for  cutting  threads  in  openings  or  coup- 
lings into  which  pipes  must  be  screwed — an  operation  which  the 
pipe-fitter  seldom  has  to  perform,  unless  a  thread  has  been  in- 
jured. The  vises  for  holding  the  pipe  should  be  such  as  will 
prevent  it  from  turning  without  crushing  it  under  any  circum- 
stances. Adjustable  vises  with  triangular-shaped  jaws  on  which 
teeth  are  cut  are  usually  employed. 

In  the  erection  of  pipe  great  care  should  be  taken  to  pre- 
serve the  proper  pitch  and  alignment,  and  the  pipes  should, 
to  appear  well,  be  screwed  together  until  no  threads  are  in 
sight.  Every  joint  should  be  screwed  six  to  eight  complete 
turns  for  the  smaller  sizes,  2"  and  under,  and  eight  to  twelve 
turns  for  the  larger  sizes,  otherwise  there  will  be  danger  of 
leakage.  It  is  a  good  plan  to  test  the  threads  on  all  pipes 
before  erection  by  unscrewing  the  coupling  and  screwing  it 
back  with  the  ends  reversed.  It  is  also  advisable  to  look 
through  each  length  of  pipe  and  see  if  it  is  clear  before  erect- 


SPECIFIC  A  TION  PROPOSA  LS—S  UGGES  TIONS.  3  5  I 

ing  in  place  ;  serious  trouble  has.  been  caused  by  dirt  or  waste 
in  pipes,  which  would  have  been  removed  had  this  precaution 
been  taken. 

In  screwing  pipes  together,  red  or  white  lead  is  often  used ; 
the  writer  believes  this  practice  to  be  generally  objectionable, 
and  to  be  of  no  especial  benefit  in  preventing  leaks.  The  lead 
acts  as  a  lubricant,  and  consequently  aids  by  reducing  the 
force  required  to  turn  the  pipe.  It  will  generally  be  found, 
however,  that  linseed  or  some  good  lubricating  oil  will  be 
equally  valuable  in  that  respect,  and  will  have  the  advantage 
of  not  discoloring  the  work. 

If  possible,  arrange  the  work  so  that  it  can  "  be  made  up  " 
with  right  and  left  elbows,  or  right  and  left  couplings.  Packed 
joints,  especially  unions,  are  objectionable,  and  likely  to  leak 
after  use.  Flange-unions,  packed  with  copper  gaskets,  should 
be  used  on  heavy  work. 

Good  workmanship  in  pipe-fitting  is  shown  by  the  perfec- 
tion with  which  small  details  are  executed,  and  it  should  be 
remembered  that  bad  workmanship  in  any  of  the  particulars 
mentioned  may  defeat  the  perfect  operation  of  the  best-de- 
signed plant. 


APPENDIX 

CONTAINING 

REFERENCES   AND   TABLES. 


LITERATURE   AND    REFERENCES. 

The  literature  devoted  to  the  subject  of  warming  and  ven- 
tilation is  quite  extensive,  dating  back  to  a  treatise  on  the 
economy  of  fuel  and  management  of  heat  by  Buchanan  in 
1815.  A  most  excellent  compilation  of  this  literature  was 
made  by  Hugh  J.  Barron  of  New  York,  in  a  paper  presented  to 
the  American  Society  of  Heating  and  Ventilating  Engineers 
at  its  first  meeting  in  January,  1895,  from  which  the  following 
list  of  books  has  been  copied  : 

A  Treatise  on  the  Economy  of  Fuel  and  Management  of  Heat. 
Robertson  Buchanan,  C.E.  Glasgow,  1815. 

Conducting  of  Air  by  Forced  Ventilation.  Marquis  de  Chabannes. 
London,  1818. 

The  Principles  of  Warming  and  Ventilating  Public  Buildings,  Dwell- 
ing-houses, etc.  Thos.  Tredgold,  C.E.  London,  1824. 

Warming,  Ventilation,  and  Sound.     W.  S.  Inman.     London,  1836. 

The  Principles  of  Warming  and  Ventilating,  by  Thos.  Tredgold,  with 
an  appendix.  T.  Bramah,  C.E.  London,  1836. 

Heating  by  the  Perkins  System.     C.  J.  Richardson.     London,  1840. 

Illustrations  of  the  Theory  and  Practice  of  Ventilation,  with  Re- 
marks on  Warming.  David  Boswell  Reid,  M.D.  London,  1844. 

A  Practical  Treatise  on  Warming  by  Hot  Water.  Chas.  Hood, 
F.R.S.  London,  1844. 

History  and  Art  of  Warming  and  Ventilating.     Walter  Bernan,  C.E, 
London,  1845. 

Warming  and  Ventilation.     Chas.  Tomlinson.     London,  1844. 

Walker's  Hints  on  Ventilation.     London,  1845. 

Practical  Treatise  on  Ventilation.     Morrill  Wyman.     Boston,  1846. 

Traite  de  la  Chaleur.  E.  Peclet.  Paris.  First  edition,  1848;  sec- 
ond edition,  3  vols,  1859. 

353 


354  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 

Practical  Method  of  Ventilating   Buildings,  with   an   appendix   on 
Heating  by  Steam  and  Water.     Dr.  Luther  V.  Bell.     Boston,  1848. 

Warming  and  Ventilation.     Chas.  Tomlinson.     London,  1850. 

Practical  Ventilation.     Robert  Scott  Burns.     Edinburgh,  1850. 

Ventilation  and  Warming.     Henry  Ruttan.     New  York,  1862. 

A  Treatise  on  Ventilation.     Robert  Richey.     London,  1862. 

American  edition  of  Dr.  Reid's  Ventilation  as  Applied  to  American 
Houses,  edited  by  Dr.  Harris.  New  York,  1864. 

A  Treatise  on  Ventilation.  Lewis  W.  Leeds.  Philadelphia,  1868; 
New  York,  1871. 

Observations  on   the    Construction    of    Healthy   Dwellings.      Capt. 
Douglas  Galton.     Oxford,  1875. 

Practical  Ventilating  and  Warming.    Jos.  Constantine.   London,  1875. 

Warming  and  Ventilation.  Chas.  Tomlinson.  London,  1876.  Sixth 
edition. 

Mechanics  of  Ventilating.     Geo.  W.  Rafter,  C.E.     New  York,  1878. 

Ventilation.     H.  A.  Gouge.     New  York,  1881. 

Ventilation.     R.  S.  Burns.     Edinburgh,  1882. 

American  Practice  in  Warming  Buildings  by  Steam.  Robert  Briggs. 
Edited  by  A.  R.  Wolf,  with  additions.  New  York,  1882. 

Steam-heating  for  Buildings.  W.  J.  Baldwin.  New  York,  1883. 
Thirteenth  edition  published  in  1893. 

The  Principles  of  Ventilation  and  Heating.  John  S.  Billings,  M.D. 
New  York,  1884. 

Heating  by  Hot  Water.     Walter  Jones.     London,  1884. 

A  Manual  of  Heating  and  Ventilation.  F.  Schuman.  New  York, 
1886. 

Ventilation.     W.  Butler.     Edited  by  Greenleaf.     New  York,  1888. 

Steam-heating  Problems  from  the  Sanitary  Engineer.  New  York, 
1888. 

Metal  Worker  Essays  on  House  Heating.     New  York,  1890. 

Heat — Its  Application  to  the  Warming  and  Ventilation  of  Buildings. 
John  H.  Mills.  Boston,  1890. 

Ventilation  and  Heating.     T.  Edwards.     London,  1890. 

Ventilation — A  Text-book  to  the  Art  of  Ventilating  Buildings. 
Wm.  Paton  Buchan.  London,  1891. 

The  Ventilating  and  Warming  of  School  Buildings.  Gilbert  B.  Mor- 
rison. New  York,  1892. 

Hot-water  Heating.     Wm.  J.  Baldwin.     New  York,  1893. 

Ventilation  and  Heating.     John  S.  Billings,  M.D.     New  York,  1893. 

Warming  by  Hot  Water,  Chas.  Hood,  C.E.  Edited  by  F.  Dye. 
London,  1894. 

In  addition  to  this  list  of  books  a  large  number  of  pam- 
phlets have  been  printed  containing  valuable  articles  on  spe- 
cial subjects.  The  scope  of  this  work  does  not  permit  any 


APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   355 


historical  review  of  the  literature  or  of  progress  and  improve- 
ments in  the  art  of  heating. 

CURRENT   LITERATURE   OF  THE  DAY. 

The  current  literature  of  the  day  relating  to  this  subject 
is  very  extensive  and  is  mainly  found  in  magazines  or  papers 
published  either  weekly  or  monthly  and  devoted  to  the  whole 
or  special  portions  of  this  industry.  In  these  are  to  be  found 
the  best  available  descriptions  of  plants,  of  new  and  improved 
methods  and  appliances,  and  in  general  all  that  relates  to  the 
best  systems  of  construction.  The  journals  devoted  to  this 
industry  provide  an  invaluable  literature  to  those  engaged  in 
the  art  of  constructing  heating  and  ventilating  apparatus. 

REFERENCES. 

Information  which  has  been  obtained  from  other  works  has 
generally  been  credited  in  the  body  of  the  book.  The  writer 
wishes,  however,  to  express  special  thanks  for  substantial 
assistance  to  the  publishers  of  the  various  papers,  and  to.  J.  J. 
Blackmore  and  J.  G.  Dudley,  members  of  the  Committee  of  the 
Boiler  Manufacturers'  Association,  as  well  as  to  other  engineers 
who  have  given  cordial  help  in  the  preparation  of  the  work. 
It  may  be  stated  that  Messrs.  Blackmore  and  Dudley  read  and 
revised  all  proofs  and  contributed  considerable  matter  of  prac- 
tical and  general  interest. 

LIST   OF  TABLES  IN  BODY   OF  BOOK. 


Air  delivered  in  pipes  of  different 

diameters 286 

Air  discharged  at  different  heights 

and  temperatures 45 

Air  discharged  under  pressure.. . .     42 
Air-flues,  area  of,  residence  heating  234 
Air-pipes,  various  diameters,  ca- 
pacity of 286 

Air  required  per  person  for  various 

standards  of  purity. . , 32 

Blowers  or  fans,  capacity  of 296 

Boiler  explosions 174 

Boilers,  steam,  proportion  of  parts  125 
Boiling-point,  different  pressures.    159 

Boiling  temperature  of  water 22 

Building  loss 56 

Chimney,  diameter  of 162 

Conduction  of  heat,  absolute 18 

Conduction  of  heat,  relative 18 

Drip-pipe,  diameter 228 


Electrical  heat,  expense  of 303 

Equalization  of  pipe  areas  for  air  287 

Exhaust-steam  heating 251 

Flue  for  indirect  heating,  area  of.  233 

Flues,  area  of 53 

Forced-blast  heating  surface,  heat 

emitted   84 

Forced-blast  test 80 

Greenhouse  heating 241 

Heat  emitted,  Peclet's  table. . .  .64-66 
Heat  emitted,  Tredgold's  experi- 
ments   76 

Heat  transmitted,  different  media.  69 

Hot-air  heating 275 

Hot- water  heaters,  proportion  of 

parts 125 

Hot-water  heating,  data 229 

Hot-water     heating,      main-pipe 

diameter.   231 

Hot-water  heating,  proportions. .  237 


356  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 


'Hot- water  pipes,  velocity  in  feet 

per  second 221 

Indirect  radiators,  air  heated 213 

Indirectjradiators.cubic  feet  heated  214 

Indirect  radiator  tests 81,  82 

Indirect  radiators,  heat  emitted. .  84 

Moisture  in  air 30 

Pipe-coverings,  tests  of. 199 

Pipe  diameter  for  great  lengths. .  226 

Power-transmission,  loss  in 264 

Radiant  heat,  amount  transmitted.  17 

Radiant  heat,  diffusion  of 17 

Radiant  heat,  relative  emissive 

powers 16 

Radiant  heat,  relative  reflecting 

powers 16 

Radiator  tests 77~79 

Radiators,  cubic  feet  of  space 

heated 208,  209 

Radiators,  diameter  of  openings..  119 
Radiators,  direct  proportioning  of  205 
Radiators,  indirect,  factors  for  ...  211 

Registers,  areas  of 53 

Registers,  commercial  sizes 280 


Relation     between    velocity     and 

pressure  of  air 45 

Relation  between  temperature  and 

color 12 

Return-pipe,  diameter 227 

Size  of  room  influence  on  ventila- 
tion      34 

Stacks,  area  of,  hot-air  heating. . .   278 

Steam-boiler,  energy  in 173 

Steam-heating,  proportions  of. ...   237 
Steam-heating  boilers,  proportions 

in  use  136 

Steam-heating  boilers,  proportions 

of  parts 125 

Steam-pipe,  area  and  diameter.. .   223 
Steam-pipe,  diameter  for  different 

lengths 226 

Temperature  produced  by  radiation 

in  warm  weather 86 

Thermometric  scales 8J 

Tubular  boiler,  dimensions  of... .    131 
Ventilation-flues,  indirect  heating  238 

Windows 54 

Wrought-iron  pipe 91 


LIST   OF  TABLES   IN  APPENDIX. 

Table  No.  I.  United  States  standard  weights  and  measures. 

II.  The  equivalent  value  of  units  in  British  and  metric  sys- 
tem, and  (IlA)  of  properties  of  gases. 

III.  Table  of  circles,  squares,  and  cubes. 

IV.  Circumferences  and  areas  of  circles. 
V.  Logarithms  of  numbers. 

VI.  Important  properties  of  familiar  substances. 
VII.  Coefficients,  strength  of  materials. 
VIII.  Properties  of  air. 
IX.  Moisture  absorbed  by  air. 

X.  Relative  humidity  of  the  air. 
XI.  Properties  of  saturated  steam. 
XII.  Composition  and  value  of  various  fuels  of  the  United  States 

XIII.  Reducing  barometric  observations  to  the  freezing-point. 

XIV.  Thermal  conductivities. 

XV.  Dimensions  of  wrought-iron,  steam,  gas,  and  water  pipe. 
XVI.  Weight  of  water  per  cubic  foot. 
XVII.  Pressure  of  water  per  square  inch  per  different  heights  in 

feet. 

XVIII.  Contents  of  pipes  in  cubic  feet  and  gallons. 
XIX.  Equalization  of  pipe  areas. 

XX.  Temperatures  of  various  localities. 
XXI.  Price  of  pipe  and  fittings. 


APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   357 

EXPLANATION   OF   TABLES. 

Of  the  tables  which  have  been  given  a  few  only  need  special 
explanation  in  order  to  fully  understand  their  use.  These  are 
as  follows:  Table  No.  V,  Logarithms  of  numbers.  This  table 
will  be  found  of  very  great  convenience  in  facilitating  any 
operation  involving  multiplication  and  division.  Thus  it  will 
be  found  in  every  case  that  the  sum  of  two  logarithms  is  the 
logarithm  of  a  number  equal  to  the  product  of  the  two  num- 
bers whose  sum  was  taken,  and  the  difference  of  two  logarithms 
is  the  logarithm  of  the  quotient  obtained  by  dividing  one  by 
the  other.  Every  logarithm  consists  of  two  parts :  a  decimal 
part,  which  is  given  in  the  table,  and  an  index  or  characteristic, 
which  must  be  prefixed.  The  index  or  characteristic  is  a  whole 
number  and  is  one  less  than  the  number  of  integral  places ; 
for  a  decimal  number  it  is  negative  and  one  more  than  the 
number  of  ciphers  between  the  decimal  point  and  the  first 
significant  figure.  Thus,  to  find  the  logarithm  of  254,  a  number 
containing  3  integral  places,  the  index  is  2,  the  decimal  part  of 
this  logarithm  found  opposite  25  and  under  4  in  the  table  is 
4048,  making  the  full  logarithm  2.4048.  If  the  number  had 
been  25.4  the  index  would  have  been  I,  the  decimal  part  as  be- 
fore. If  the  number  had  been  0.0254,  the  index  would  have 
been  minus  2,  the  decimal  part  the  same  as  before. 

As  an  illustration  showing  how  to  multiply  by  logarithms, 
multiply  254  by  2.48.     We  have  : 

The  logarithm  of  254  =  2.4048 

"  2.48  =  0.3945 

Log.  of  product  =  2.7993 

The  sum  of  these  two  logarithms,  which  is  the  logarithm  of 
the  product,  is  equal  to  2.7993.  The  index,  or  number  2,  is  of 
use  in  showing  that  there  are  three  figures  or  integral  places  in 
the  result.  To  find  the  logarithm,  look  in  the  table  for  the 
number  next  smaller  than  7993 ;  in  this  case  the  result  is  exact 
and  is  found  opposite  63  in  the  column  marked  zero,  indicating 
that  the  product  is  630;  the  actual  product  of  these  numbers 
is  slightly  less  than  this,  the  difference,  however,  being  scarcely 
ever  of  any  practical  importance.  Had  our  number  been  7994, 
it  would  have  been  one  greater  than  7993  and  6  less  than  the 
logarithm  of  the  next  number.  In  that  case  our  number  would 


358  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 

have  been  630^-,  which,  reduced  to  a  decimal,  would  have  been 
the  number  to  consider  as  the  product.  The  logarithm  of  a 
power  can  be  found  by  multiplying  the  logarithm  by  the  num- 
ber which  represents  the  power  and  the  logarithm  of  a  root  by 
dividing  by  the  index  of  the  root. 

Thus,  to  raise  368  to  the  fifth  power,  we  have  : 

Log.  368  =    2.5658 
Multiply  by  5 

Log.  5th  power  =  12.8290 
No.  =  674^-  expanded  to  13  places  =  6745000000000. 

To  extract  5th  root :  368  :— 

Log.  368  =  2.5658 

Divide  by  5  =  0.51316  =  log.  of  root 
Root  —  3.259 

In  general  the  table  will  be  found  to  afford  an  easy  method 
of  dividing  or  multiplying,  and  it  will  be  well  worth  while  to 
become  master  of  its  use. 

The  table  which  is  printed  in  the  book  is  correct  for  4  places 
of  figures  only,  but  tables  of  7  and  even  13  places  have  been 
printed. 

The  four-place  table  can  be  used  with  confidence  for  all 
operations  not  requiring  extreme  accuracy.  It  will  in  almost 
every  case  be  found  sufficiently  accurate  for  all  practical  prob- 
lems of  designing. 

The  method  of  using  Tables  Nos.  IX  and  X  to  determine  the 
amount  of  moisture  in  the  air  has  been  quite  fully  explained 
on  page  30.  The  method  of  using  Table  No.  XI.  (properties 
of  saturated  steam)  has  been  fully  explained  on  page  120.  The 
reader  should  note  that  the  steam-pressure  tabulated  is  that 
above  a  vacuum,  and  not  the  reading  of  a  pressure-gauge.  The 
pressure-gauge  reads  from  the  atmosphere,  which  is  generally 
14.7  pounds  above  zero  ;  hence,  in  order  to  use  the  table,  add 
14.7  pounds  to  the  steam-gauge  reading  for  the  pressure  above 
zero.  The  other  quantities  will  be  quite  readily  understood. 

The  table  for  equalization  of  pipe  areas  has  been  quite  fully 
explained  on  page  287.  The  number  of  pipes  of  the  size,  as 
shown  in  the  side  column,  required  to  give  an  equivalent  area 
to  the  one  in  the  top  column  is  given  by  the  numbers.  Thus 
14.7  pipes  i  inch  in  diameter  have  a  carrying  capacity  equfva- 
'lent  to  that  of  one  pipe  3  inches  in  diameter. 


APPENDIX  CONTAINING  REFERENCES  AND  TABLES.  359 


X     U 


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PQ 
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ii 

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CUBIC 

Bushels  to 
Hecto- 
litres. 

M  in  r^*  o  I-H  T  o  co   •-« 
Too  NO   **   m  O  enco 

o<  T  r^  o  M  TO  o  i- 

m  O  m  O  O   »••  O   i-if^ 
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e  Coast  Survey  office,  whose  length  at  59°.  62 
•  British  yard. 
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direct  comparison.  The  British  Avoirdupois 

se  in  the  United  Slates  is  equal  to  the  British 

Cubic 
Yards  to 
Cubic 
Metres. 

in  o  Too  en  r^  N  o   « 
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r^mw  o<x>  mcn^oo 

^          OS         TcTlS 

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11    II    II    II    II    II    II    II    II 
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WEIGHT. 

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Ounces  to 
Grammes. 

ooo  TM  o  Oilmen 
T  O  T  O  TOO  cnoo  en 
eno  O  en  r^.  o  T  i^-  IH 
O  o  M  •-  —  M040<cn 
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t*c*J      «o    .2 

*  SQUARE. 

Acres  to 
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TOO    N  O    O    TOO    N  O 

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eno  OM  moo  >-i  T  t^ 

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ii  £  D  „;  o  c<  oo  Tf-i-i  r~*  en  o  m 

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r  o*  Is  C*  *i    6  «  M  en  T  m  in  O  t*» 

Avoirdu- 
pois 
Pounds  to 
Kilo- 

pnunmes. 

0s  Ocx)   f^»  O  O   in  T  en 
mi-i  r^cnc>mi-i  r^en 
en  r^-  o  ^1*  r^»  «   moo  N 
inOO    —  O    OJr^NQO 
T  O  enco  N  i^  w  o  O 

6oM*HCMNenenT 

mary  length  is  the  Troughton  scale  i 
in  use  in  the  United  States  is  therefo 
mary  weight  is  the  Troy  pound  of  t 
d  from  the  British  standard  Troy  pou 
is  7000  grains  Troy. 
?rain  Avoirdupois,  and  the  pound  A^ 
litres.  The  British  bushel  =  36.3477 

£  U           •O|--'-i~MMOlenen 

*  rt.^  £    oco  r^o  m  T  en  M  - 
JJ  3  U  ^    M    una°    *•*    1"  ^  °    ^^ 
3  '-ft  C  Q    Oao  r^f^O  m  m  T  en 
o>  o      e         i-i  w  en  T  mo  r^ao 

Avoirdu- 
pois 
Ounces  to 
Grammes. 

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TOTOTOTOT 
eno  O  en  t^  o  «T  !••  M 

ooo  »neni-i  Oooo  u> 
M   moo  i->   T  t-^  O  M  in 

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.    Menini^-aoG>-enm 
£•   •    x    inOmOmi-iO*-O 
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,O  w  «'O  oi    Oin  o<  co  in  M  co 
J^Ug        ~~«enenTmin 

Grains  to 
Milli- 
grammes. 

1 

O">co  oo  r^o  m  T  T  en 
oo  t-^o  inTcnM  -  O 

r~.men«    Ot^men>-i 

T  O  T  O  enoo  enco  en 
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II    II    II    II    II    II    II    II    II 
i—  N   enTmo   r^oo   O* 

II    II    II    II    II    II    II    II    II 
M  01  en  T  mo  r-^oo  0s 

LINEAR. 

Miles  to 
Kilometres 

m  ^  -^-  O^  TOO   enuo   W 
cno  O  en  r^  o  T  f^  « 
foo  oo   r-^O  O   m  T  T 
—   c>«   en  T  mo   r^oo 
C^CO    TOO    MOO    T 

1-1  en  TO  06  O>  >-i  N  T 

The  only  authorized  material  standard  of  custr 
Fahr.  conforms  to  the  British  standard.  The  yard 
The  only  authorized  material  standard  of  custo 
not  suitable  for  a  standard  of  mass.  It  was  derive 
pound  was  also  derived  from  the  latter,  and  contaii 
The  grain  Troy  is  therefore  the  same  as  the 
pound  Avoirdupois.  The  British  gallon  =  4-54346 

CAPACITY. 

Gallons  to 
Litres. 

TOO    01  O    O    TOO    01  O 

TOO   en  r^  M  O   O   in  O 
ir>  O  O   i-"  r~»  M  oo  enco 
co   1^-mTM   i-i    OQOO 
r^-meni-i  or^»TM   O 

Yards  to 
Metres. 

M   Tmr^Oi-i  enmo 

TOO    Ci  O    O    TOO    CJ  \X5 

Too  en  r^  o»  O   O  m  c> 
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360  APPENDIX  CONTAINING  REFERENCES  AND  TABT.ES. 


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APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   361 


TABLE  No.  II. 

EQUIVALENT   VALUE    OF   UNITS   IN    BRITISH    AND   METRIC 

SYSTEMS. 

One      foot  =  12  inches  =  30.48  centimetres  =  0.3048  metre. 

One  metre  =  100  centimetres  =  3.2808  ft.  =  1.936  yd. 

One     mile  —  5280  ft.  —  1750  yd.  =  1609.3  metre. 

One      foot  =  144  sq.  in.  =  1/9  sq.  yd.  =  929  sq.  centimetres 

—  .0929  sq.  metre. 
One    sq.    metre  =  10000  sq.  centimetres  =  1.1960  sq.  yds.  = 

10.764  sq.  ft. 
One   cubic    foot  =  1728    sq.    in.  =  2832    cu.    centimetres  = 

0.02832  cu.  metres. 

One  cubic  metre  =  35.314  cu.  ft.  =  1.3079  cu.  yds. 
One  pound  adv.  =  7000  grains  =  16   oz.  —  453.59   grains  — 

0-45359  kilograms. 
One       kilogram  =  1000  grams  =  2.2046  Ibs.  =  15432  grains  = 

35.27  oz.  adv. 

COMPOUND    UNITS. 

One  foot-pound  =  0.13826  kg.-mt.  =  1,3826  gr.-c.  =  1/778  B. 

T.  U. 

One  horse-power  =  33000  ft. -pound  per  minute  =  746  Watts. 
One    kilogram-metre  =  7.233   ft.-lb  =  723.300  gr.-c.  =  1/426 

calorie. 

One  gram-centimetre  =  i/iooooo  kg.-mt.  =  .00007233  ft.-lb. 
One      calorie  =426.10   kg.-mt.  =  3.9672    B.    T.    U.  =  42000 

million  ergs  per  second  =  42  Watts. 
One  B.  T.  U.  =  778  ft.-lbs.  =  0.2521  cal.  =  10820  mil.  ergs.  =» 

107.37  kg.-m. 
One  calorie  per  sq.  metre  =  0.3686  B.  T.  U.  per  sq.  ft. 

C.  G.  S.  SYSTEM. 

One  dyne  =  one  gram  /98i  =  0.00215  Ib. 

One     erg.  =  I  dyne  X  I  cent.  =  0.0000707  ft.-lb. 

One  Watt  =  10  mil.  ergs,  per  sec.  —  0738  ft.-lbs.  per  sec.  = 

h.  p.  7746. 
One  h.  p.  =-  746  Watts. 


362  APPENDIX  CONTAINING  REFERENCES  AND  TABLES, 

TABLE  No.  HA. 

TABLE   OF   PROPERTIES   OF   GASES. 


Element  or  Compound. 

Symbol  by 
Volume. 

Atomic 
Weights. 

Cubic 
feet 
per  Ib. 
at  62°. 

Weight 
per.    cu. 
ft.  at  62°. 
Lbs. 

Specific 
Gravity 
at  62°. 
Water  =  i 

Relative 
Density. 

O 

N 
H 

C 
P 

S 
Si 
79N+2iO 
H2O 
NH3 
CO 

C02 

CH2 
CH4 
S02 
SH2 
S2C 

Oa 

16 

14 
I 

19 
12 

31 

32 
14 

18 

17 

28 

44 

14 
16 
64 

34 
76 
24 

11.88 

13-54 
189.7 

15.84 
6.119 
5-932 
13.55* 
I3-I4 
2I.O7 
22.3 
13-6 

8.64 

13.587 
23.757 
6.463 

5.582 
2.487 
7-97 

0.0814 
0.0738 
0.00527 

0.63131 
0.16337 
o.  16861 

0.07378 

0.0761 

0.04745 
0.0448 
0.07364 

0.11631 

0.0736 
0.04209 

0.15536 

0.17918 
0.40052 
0.12648 

0.001350 
O.OOII85 
0.0000846 
0.001607 
O.OOIOI3 
O.OO2622I 
o  002705 
0.001184 
O.OOI22I 
0.0007613 
O.OOII8 
0.002369 

O.OOI87 

0.001181 

O.OOO675 
0.002493 
O.002877 
0.00643 
O.OO2O3 

1.10563 
0.97137 
0.06926 
I.3II8 
0.82323 
2.1877 
2.2150 
1.01032 
1.  0000 

0.6253 
0.5892 
0.9674 

1.52901 

0.96710.4 

0.55306 
1.54143 
2.3943 
5.3007 
1.64656 

Hydrogen   

Carbon  •  

Phosphorus      .  .    .... 

Air                 

W^ater  vapor  

Ammonia      

Carbon  monoxide.  .  .  . 
(Carbonic  oxide) 

(Carbonic  acid) 
Olefiant  gas    

Marsh  gas  

Sulphurous  acid 

Sulphuretted  hydrogen 
Bisulphuret  of  carbon. 

*  By  this  table  there  would  be  12.75  cubic  feet  of  air  at  32°  per  pound. 


APPENDIX  CONTAINING  REFERENCES  AND  TABLES.  363 


TABLE  No.  III. 

TABLE  OF   CIRCLES,    SQUARES,    AND   CUBES. 


n 
Diam. 

fur 
Circumf. 

ir 
n*~ 
4 

Area. 

•• 

Square. 

«» 
Cube. 

v« 

Sq.  Root. 

V* 

Cub.  Rt. 

.O 

3.142 

0.7854 

.000 

I  .OOO 

.0000 

I.  0000 

.1 

3-456 

0.9503 

.210 

I-33I 

.0488 

1.0323 

.2 

3-770 

I.I3IO 

.440 

1.728 

-0955 

I  .0627 

•  3 

4.084 

I  3273 

.690 

2.197 

.1402 

1.0914 

•4 

4.398 

1-5394 

.960 

2-744 

.1832 

I.II87 

•  5 

4.712 

1.7672 

2.250 

3-375 

•2247 

I.I447 

.6 

5-027 

2.0106 

2.560 

4.096 

.2649 

1.1696 

-7 

5-341 

2.2698 

2.890 

4.913 

.3038 

I-I935 

.8 

5.655 

2-5447 

3.240 

5-832 

.3416 

1.2164 

•9 

5.969 

2-8353 

3.610 

6.859 

.3784 

1.2386 

2.0 

6.283 

3.T4I6 

4-000 

8.000 

.4142 

1.2599 

2.1 

6-597 

3-4636 

4.410 

9.261 

.4491 

1.2806 

2.2 

6.912 

3-8013 

4.840 

10.648 

.4832 

1.3006 

2-3 

7.226 

4.1543 

5-290 

12.  167 

.5166 

1.3200 

2.4 

7-540 

4-5239 

5.760 

13.824 

.5492 

1.3389 

2.? 

7-854 

4.9087 

6.2=;o 

15.625 

.5811 

1.3572 

2.6 

8.168 

5.3093 

6.760 

17.576 

.6125 

I-375I 

2.7 

8.482 

5.7256 

7.290 

19.683 

-6432 

1.3925 

2.b 

8.797 

6.1575 

7.840 

21.952 

.6733 

1.4095 

2.9 

9.111 

6.6052 

8.410 

24.389 

.7029 

1.4260 

3.0 

9-425 

7.0686 

9.00 

27.000 

-7321 

1.4422 

3-i 

9-739 

7-5477 

9.61 

29.791 

•7607 

1.4581 

3-2 

10.053 

8.0425 

10.24 

32.768 

.7889 

1-4736 

3-3 

10.367 

8.5530 

10.89 

35-937 

.8166 

1.4888 

3-4 

10.681 

9.0792 

11.56 

39-304 

•8439 

1.5037 

3-5 

10.996 

9.6211 

12.25 

42.875 

.8708 

1.5183 

3-6 

11.310 

10.179 

12.96 

46.656 

.8974 

1.5326 

3-7 

11.624 

10.752 

13.69 

50-653 

•9235 

i  .  5467 

3-8 

n.938 

U-34I 

14.44 

54-872 

•9494 

1.5605 

3-9 

12.252 

11.946 

15.21 

59-3I9 

-9748 

i.  5741 

4.0 

12.566 

12.566 

16.00 

64.000 

2.OOOO 

1.5874 

4.1 

12.881 

13.203 

16.81 

68.921 

2.0249 

1.6005 

4.2 

13-195 

13-854 

17.64 

74.088 

2.0494 

1-6134 

4-3 
4-4 

13  509 
13-823 

14-522 
15-205 

18.49 
19.36 

79-507 
85  -  184 

2.0736 
2.0976 

1.6261 
1.6386 

4-5 

14-137 

15.904 

20.25 

91.125 

2.I2I3 

1.6510 

4.6 

14.451 

16.619 

21.  16 

97.336 

2  .  1448 

1.6631 

4-7 

14.765 

17-349 

22.09 

103.823 

2.1680 

i  6751 

3^4  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 
CIRCLES,    SQUARES,    AND   CUBES—  Continued. 


n 
Diam. 

nit 
Circumf. 

*; 

Area. 

«" 

Square. 

[ 

•• 

Cube. 

v« 

Sq.  Root. 

s 
Y'n 

Cub.  Rt. 

4.8 

15.080 

18.096 

23.04 

110.592 

2.1909 

.6869 

4-9 

15-394 

18.857 

24.01 

117.649 

2.2136 

.6985 

5-0 

15.708 

19-635 

25.00 

125.000 

2.2361 

•  7100 

5-i 

16.022 

20.428 

26.OI 

132-651 

2.2583 

•7213 

5-2 

16.336 

21.237 

27.04 

140.608 

2  .  2804 

•7325 

5-3 

16.650 

22.062 

28.09 

148.877 

2.3022 

•7435 

5-4 

16.965 

22.902 

29.16 

157.464 

2.3238 

•7544 

5-5 

17.279 

23.758 

30.25 

166.375 

2.3452 

.7652 

5;6 

17-593 

24.630 

31-36 

I75.6I6 

2.3664 

.7758 

5*7 

17.907 

25.518 

32-49 

185.193 

2.3875 

.7863 

5-8 

18.221 

26.421 

33-64 

I95.II2 

2.4083 

.7967 

5-9 

18.535 

27.340 

34.81 

205.379 

2.4290 

.8070 

6.0 

18.850 

28.274 

36.00 

2X6.000 

2.4495 

.8171 

6.1 

19.164 

29.225 

37-21 

226.981 

2.4698 

.8272 

6.2 

19.478 

30.191 

38-44 

238.328 

2.4900 

•8371 

6.3 

19.792 

31.173 

39-69 

250.047 

2.5100 

.8469 

6.4 

20.106 

32.170 

40.96 

262.144 

2.5298 

.8566 

6.5 

20.420 

33.183 

42.25 

274-625 

2-5495 

.8663 

6.6 

20-735 

34-212 

43.56 

287.496 

2.5691 

.8758 

6.7 

21.049 

35.257 

44.89 

300.763 

2.5884 

.8852 

6.8 

21.363 

36.317 

46.24 

314.432 

2.6077 

.8945 

6.9 

21.677 

37.393 

47-6i 

328.509 

2.6268 

.9038 

7.0 

21.991 

38.485 

49.00 

343.000 

2.6458 

.9129 

7-i 

22.305 

39-592 

50.41 

357-9" 

2.6646 

.9220 

7.2 

22.619 

40.715 

51.84 

373-248 

2.6833 

.9310 

7-3 

22.934 

41.854 

53-29 

389-017 

2.7019 

•9399 

7-4 

23-248 

43.008 

54.76 

405  •  224 

2.7203 

.9487 

7-5 

23.562 

44.179 

56.25 

421.875 

2.7386 

-9574 

7.6 

23.876 

45-365 

57.76 

438.976 

2.7568 

.9661 

7-7 

24.190 

46.566 

59-29 

456.533 

2-7749 

•  9747 

7.8 

24-504 

47.784 

60.84 

474-552 

2.7929 

1.9832 

7-9 

24.819 

49.017 

62.41 

493-039 

2.8107 

1.9916 

8.0 

25.133 

50.266 

64.00 

512.000 

2.8284 

2.OOOO 

8.1 

25-447 

51.530 

65.61 

53I-44I 

2.8461 

2.0083 

8.2 

25-761 

52.810 

67.24 

55L468 

2.8636 

2.0165 

8.3 

26.075 

54-106 

68.89 

57L787 

2.8810 

2.0247 

8.4 

26.389 

55.418 

70.56 

592  •  704 

2.8983 

2.0328 

8-5 

26.704 

56.745 

72.25 

614.125 

2-9155 

2.0408 

8.6 

27.018 

58.088 

73.96 

636.056 

2.9326 

2.0488 

8.7 

27.332 

59-447 

75.69 

658.503 

2.9496 

2.0567 

8.8 

27.646 

60.821 

77-44 

681.473 

2.9665 

2.0646 

8.9 

27.960 

62.211 

79-21 

704.969 

2.9833 

2.0724 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   365 
CIRCLES,    SQUARES,    AND   CUBES—  Continued. 


n 

Diam. 

tat 
Circumf. 

•*4 

Area. 

«2 

Square. 

«3 

Cube. 

*Tn 
Sq.  Root. 

V; 

Cub.  Rt. 

9  ° 

23.274 

63.617 

Sl.OO 

729.000 

3.0000 

2.0801 

Q.I 

28.588 

65-039 

82.81 

753.571 

3.0166 

2.0878 

9.2 

28.903 

66.476 

84.64 

778.688 

3  0332 

2.0954 

9-3 

29.217 

67.929 

86.49 

804.357 

3-0496 

2.1029 

9-4 

29-53I 

69.398 

88.36 

830.584 

3.0659 

2.II05 

9-5 

29.845 

70.882 

90.25 

857.375 

3.0822 

2.1179 

9.6 

30.159 

72.382 

92.16 

884.736 

3.0984 

2.1253 

9-7 

30.473 

73.898 

94.09 

912.673 

3-"45 

2.1327 

9.8 

30.788 

75-430 

96.04 

941.192 

3.1305 

2.1400 

9-9 

31.102 

76.977 

98.01 

970.299 

3.1464 

2.1472 

IO.O 

3i-4r6 

78  .  540 

IOO.OO 

lOOO.OOO 

3.1623 

2-1544 

10.  I 

3I-730 

80.119 

102.01 

1030  .  301 

3.1780 

2.1616 

10.2 

32.044 

81.713 

104.04 

1061.208 

3-1937 

2.1687 

10.3 

32.358 

83.323 

106.09 

1092.727 

3.2094 

2.1757 

10.4 

32.673 

84.949 

108.16 

1124.863 

3.2249 

2.1828 

10.5 

32.987 

86.590 

110.25 

1157.625 

3.2404 

2.1897 

10.6 

33-301 

88.247 

112.36 

1191.016 

3-2558 

2.1967 

10.7 

33.6I5 

89.920 

114.49 

1225.043 

3.27II   2.2036 

10.8 

33-929 

91.609 

116.64 

1259.712 

3.2863 

2.2104 

10.9 

34-243 

93.313 

118.81 

1295.029 

3.3015 

2.2172 

II.  0 

34-558 

95-033 

121.00 

1331.000 

3.3166   2.223Q 

li.  i 

34.872 

96.769 

123.21 

1367.631 

3.3317 

2.2307 

II.  2 

35-186 

98.520 

125.44 

1404.928 

3.3466 

2.2374 

II-  3 

35-500 

100.29 

127.69 

1442.897 

3.3615 

2  .  2441 

11.4 

35.814 

102.07 

129.96 

1481.544 

3.3/64 

2.25O6 

n.  5 

36.128 

103.87 

132.25 

1520.875 

3-3912 

2.2572 

li.  6 

36.442 

105.68 

134.56 

1560.896 

3-4059 

2.2637 

li.  7 

36.757 

107.51 

136.89 

1601.613 

3.4205 

2  .  27O2 

II.  8 

37-071 

109.36 

139.24 

1643.032 

3.4351 

2.2766 

11.9 

37.385 

'111.22 

141.61 

1685.159 

3.4496 

2.2831 

12.0 

37.699 

113.  10 

144.00 

1728.000 

3.4641 

2.2894 

12.  1 

38.013 

"4-99 

146.41 

1771.561 

3.4785 

2.2957 

12.2 

38.327 

116.90 

148.84 

1815.848 

3.4928 

2.3O2I 

12.3 

38.642 

118.82 

151.29 

1860.867 

3  5071 

2.3084 

12.4 

38.956 

120.76 

153.76 

1906.624 

3-5214 

2.3146 

12-5 

39.270 

122.72 

156.25 

1953.125 

3-5355 

2.3208 

12.6 

39.584 

124.69 

158.76 

2000.376 

3.5496 

2.3270 

12.7 

39-898 

126.68 

161.29 

2048.383 

3.5637 

2.3331 

12.8 

40.212 

128.68 

163.84 

2097.152 

3-5777 

2.3392 

12.9 

40.527 

130.70 

166.41 

2146.689 

3.59I7 

2.3453 

13.0 

40.841 

132.73 

169.00 

2197.000 

3-6056 

2.3513 

13-1 

41-155 

134-78 

171.61 

2248.091 

3.6194 

2-3573 

,43-2 

41.469 

136.85 

174.24 

2299.968 

3-6332 

2.3633 

366  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 
CIRCLES,    SQUARES,    AND    CUBES— Continued. 


n 
Diam. 

rnr 
Circumf. 

7T 
»«- 

4 
Area. 

«« 

Square. 

«3 

Cube. 

v« 

Sq.  Root. 

3 
K 

Cub.  Rt. 

13-3 

4L783 

138.93 

176.89 

2352.637 

3  •  6469 

2.3693 

13-4 

42.097 

141.03 

I79-56 

2406  .  104 

3.6606 

2.3752 

13-5 

42.412 

143.14 

182.25 

2460.375 

3.6742 

2.3811 

13-6 

42.726 

145.27 

184.96 

2515.456 

3-6878 

2.3870 

13-7 

43.040 

147.41 

187.69 

257L353 

3.7013 

2.3928 

13-8 

43-?54 

149-57 

190.44 

2628.072 

3.7148 

2.3986 

13-9 

43  .  668 

I5I-75 

193.21 

2685.619 

3.7283 

2.4044 

14.0 

43.982 

153-94 

196.00 

2744.000 

3.7417 

2.4101 

14.1 

44.296 

156.15 

198.81 

2803.221 

3.7550 

2.4I59 

14.2 

44.611 

158.37 

201.64 

2863.288 

3.7683 

2.4216 

14-3 

44-925 

160.61 

204.49 

2924.207 

3.7oI5 

2.4272 

14.4 

45-239 

162.86 

207.36 

2985.984 

3-7947 

2.4329 

14.5 

45-553 

165.13 

210.25 

3048.625 

3.8079 

2.4385 

14.6 

45.867 

167.42 

213.  16 

3112.  136 

3.82IO 

2.4441 

14-7 

46.181 

169.72 

216.09 

3176.523 

3.8341 

2-4497 

14.8 

46.496 

172.03 

219.04 

3241.792 

3.847I 

2-4552 

14.9 

46.810 

174-37 

222.  OI 

3307-949 

3  .  8600 

2.4607 

15-0 

47-124 

176.72 

225.00 

3375-000 

3-8730 

2  .  4662 

I5-I 

47.438 

179.08 

228.01 

3442.951 

3-8859 

2.4717 

15.2 

47-752 

181.46 

231.04 

3511.808 

3.8987 

2.4772 

15-3 

48.066 

183.85 

234.09 

3581.577 

3-9II5 

2.4825 

15-4 

48.381 

186.27 

237.16 

3652.264 

3.9243 

2.4879 

15-5 

48.695 

188.69 

240  25 

3723.875 

3-9370 

2-4933 

15.6 

49-009 

191.13 

243.36 

3796.416 

3-9497 

2.4986 

15-7 

49-323 

193-59 

246.49 

3869.893 

3.9623 

2.5039 

15-8 

49-637 

196.07 

249.64 

3944.312 

3-9749 

2.5092 

15-9 

49-951 

198.56 

252.81 

4019.679 

3-9875 

2.5146 

16.0 

50.265 

201.06 

256.00 

4096  .  ooo 

4.0000 

2.5198 

16.1 

50.580 

203.58 

259.21 

4173.281 

4-0125 

2.5251 

16.2 

50.894 

206.12 

262.44 

4251.528 

4.0249 

2.5303 

16.3 

51.208 

208.67 

265.69 

4330.747 

4.0373 

2.5355 

16.4 

51-522 

211.24 

268  .  96 

4410.944 

4  -  0497 

2.5406 

16.5 

51.836 

213-83 

272.25 

4492.125 

4.0620 

2.5458 

16.6 

52.150 

216.42 

275-56 

4574.296 

4-0743 

2.5509 

16.7 

52.465 

219.04 

278.89 

4657.463 

4.0866 

2.5561 

16.8 

52.779 

221.67 

282.24 

4741.632 

4.0988 

2.5612 

16.9 

53-093 

224.32 

285.61 

4826  .  809 

4.1110 

2.5663 

17-  o 

53-407 

226  98 

289.00 

4913.000 

4.1231 

2.5713 

17.1 

53.721 

229.66 

292.41 

5000.211 

4.1352 

2.5763 

17.2 

54.035 

132.35 

295-84 

5088.448 

4-H73 

2.5813 

17-3 

54-350 

235-06 

299.29 

5177.717 

4-1593 

2.5863 

17-4 

54-664 

237-79 

302.76 

5268.024 

4.I7I3 

2.5913 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   367 
CIRCLES,    SQUARES,    AND   CUBES— 


n 
Diam. 

nir 
Circumf. 

«*- 

4 
Area. 

«2 

Square. 

«3 

Cube. 

f~n 
Sq.  Root. 

3 

Vm 

!  Cub.Rt. 

17-5 

54-978 

240.53 

306.25 

5359.375 

4.1833 

2.5963 

17-6 

55.292 

243.29 

309.76 

5451.776 

4.1952 

2.6012 

17.7 

55-606 

246.06 

3I3.29 

5545.233 

4.2071 

2.  6o6l 

17-8 

55-920 

248.85 

316.84 

5639.752 

4.2190 

2.6109 

17-9 

56.235 

251.65 

320.41 

5735-339 

4-2308 

2.6158 

18.0 

56.549 

254-47 

324.00 

5832.000 

4.2426 

2  .  6207 

18.1 

56.863 

257.30 

327.61 

5929.741 

4.2544 

2.6256 

18.2 

57-177 

260.16 

33L24 

6028.568 

4.2661 

2.6304 

18.3 

57.491 

263.02 

334.89 

6128.487 

4.2778 

2.6352 

18.4 

57.805 

265.90 

338.56 

6229.504 

4.2895 

2  .  6401 

18.5 

58.119 

268.80 

342.25 

6331-625 

4-3012 

2.6448 

18.6 

58.434 

271.72 

345.96 

6434.856 

4.3I2S 

2.6495 

18.7 

58.748 

274.65 

349.69 

6539-203 

4.3243   2.6543 

18.8 

59.062 

277-59 

353.44 

6644.672 

4-3359  !  2.6590 

18.9 

59-376 

280.55 

357-21 

6751.269 

4.3474 

2.6637 

19.0 

59-690 

283.53 

361.00 

6859.000 

4.3589 

2.6684 

19.1 

60.004 

286.52 

364-81 

6967.871 

4-3703 

2.6731 

19-2 

60.319 

289.53 

368.64 

7077.888 

4.3818 

2.6777 

19-3 

60.633 

292.55 

372-49 

7189.057 

4-3932 

2.6824 

19-4 

60.947 

295.59 

376.36 

7301.384 

4.4045 

2.6869 

19.5    61.261 

298.65 

380.25 

7414.875 

4.4I59 

2.6916 

I9-6    61.575 

301  .  72 

384.16 

7529-536 

4.4272 

2.6962 

19.7    61.889 

304.31 

388.09 

7645-373 

4.4385 

2.7008 

19.8 

62.204 

307.91 

392.04 

7762.392 

4.4497 

2.7053 

19-9 

62.518 

3".03 

396.01 

7880.599 

4.4609 

2.7098 

20.0 

62.832 

314.16 

400.00 

8000.000 

4-4721 

2.7144 

20.1 

63.146 

317.31 

404.01 

8I2O.6OI 

4.4833 

2.7189 

20.2 

63.460 

320.47 

408.04 

8242.408 

4-4944 

2.7234 

20.3 

63.774 

323.66 

412.09 

8365-427 

4.5055 

2.7279 

20.4 

64.088 

326  85 

416.16 

8489.664 

4.5I66 

2.7324 

20.5 

64.403 

330.06 

420.25 

8615.  12^ 

4.5277 

2.7368 

20.6 

64.717 

333-29 

424.36 

8741.816 

4.5387 

2.7413 

20.7 

65.031 

336.54 

428.49 

8869.743 

4-5497 

2-7457 

20.8 

65.345 

339-80 

432.64 

8989.912 

4.5607 

2.7502 

20.9 

05.659 

343.07 

436.81 

9129.329 

4.5716 

2-7545 

21.0 

65-973 

346.36 

441.00 

9261  .OOO 

4-5826 

2.7589 

21.  1 

66.288 

349.67 

445.21 

9393.931 

4-5935 

2.7633 

21.2 

66.602 

352.99 

449.44 

9528.128 

4-6043 

2.7676 

21.3 

66.916 

356.33 

453-69 

9663.597 

4-6152 

2.7720 

21.4 

67.230 

359-68 

457.96 

9800.344 

4.6260 

2.7763 

21-5 

67.544 

363-05 

462.25 

9938.375 

4.6368 

2.7806 

21.6 

67.858 

366.44 

466.56 

10077.696 

4.6476 

2.7849 

21.7  1    68.173 

369.84 

470.89 

I02I8.3I3 

4.6583 

2.7893 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 
CIRCLES,    SQUARES,    AND    CUBES— Continued. 


n 
Diam. 

•HIT 

Circumf. 

JT 
««- 

4 
Area. 

n* 
Square. 

n3 
Cube. 

v« 

Sq.  Root. 

a 

*H 

Cub.  Rt. 

21.8 

68.487 

373-25 

475-24 

10360.232 

4  .  6690 

2-7935 

21-9 

68.801 

376.69 

479-61 

10503.459 

4.6797 

2.7978 

22.0 

69.115 

380.13 

484.00 

10648.000 

4.6904 

2  .  8021 

22-1 

69.429 

383-60 

488.41 

10793.861 

4-70II 

2  .  8063 

22.2 

69.743 

387.08 

492.84 

10941.048 

4.7117 

2.8105 

22-3 

70.058 

390.57 

497  -  29 

11089.567 

4.7223 

2.8147 

22.4 

70.372 

394.08 

501.76 

11239.424 

4.7329 

•2.8189 

22.5 

70.686 

397.61 

506.25 

11390.625 

4-7434 

2.8231 

22.6 

71.000 

401.15 

510.76 

11543.176    4-7539 

2.8273 

22.7 

71.314 

404-71 

515-29 

11697.083 

4.7644 

2.8314 

22.8 

71.268 

408  .  28 

519.84 

11852.352 

4-7749 

2.8356 

22.Q 

71.942 

411.87 

524.41 

12008.989 

4.7854 

2.8397 

23.O 

72.257 

4I5.48 

529.00 

12167.000 

4-7958 

2.8438 

23-1 

72-571 

419.  10 

533-6i 

12326.391 

4.8062 

2.8479 

23-2 

72.885 

422.73 

538.24 

12487.168 

4.8166 

2.8521 

23-3 

73.199 

426.39 

542.80 

12649.337 

4-8270 

2.8562 

23-4 

73-5I3 

430.05 

547-56 

12812.904 

4-8373 

2.8603 

23-5 

73.827 

433-74 

552.25 

12977.875 

4.8477 

2  .  8643 

23.6 

74.142 

437-44 

556.96 

13144.256 

4-8580 

2.8684 

23-7 

74.456 

441.15 

561.69 

13312.053 

4.8683 

2.8724 

23.8 

74-770 

444.88 

566.44 

13481.272 

4.8785 

2.8765 

23-9 

75.084 

448.63 

571.21 

13651.919 

4.8888 

2  .  8805 

24.0 

75.398 

452  39 

576.00  • 

13824.000 

4.8990 

2.8845 

24-1 

75-712 

456.17 

580.81 

13997.521 

4  .  9092 

2.8885 

24-2 

76.027 

459.96 

585.64 

14172.488 

4-9J93 

2.8925 

24-3 

76.341 

463.77 

590.49 

14348.907 

4.9295 

2.8965 

24.4 

76.655 

467  .  60 

595.36 

14526.784 

4.9396 

2  .  9004 

24-5 

76.969 

471.44 

600.25 

14706.125 

4-9497 

2  .  9044 

24.6 

77.283 

475-29 

605.16 

14886.936 

4.9598 

2.9083 

24.7 

77.597 

479.16 

610.09 

15069.223 

4.9699 

2.9123 

24-8 

77.911 

483-05 

615.04 

15252.992 

4.9799 

2.9162 

24-9 

78.226 

486.96 

620.01 

15438.249 

4.9899 

2.92OI 

25.0 

78.540 

490.87 

625.00 

15625.000 

5.0000 

2.9241 

25.1 

78.854 

494.81 

630.01 

15813-251 

5-0099 

2.9279 

25.2 

79-168 

498.76 

635-04 

16003.008 

5.0199 

2.9318 

25-3 

79.482 

502.73 

640.09 

16194.277 

5.0299 

2-9356 

25-4 

79.796 

506.71 

645.16 

16387.064 

5-0398 

2-9395 

25-5 

80.  Ill 

510.71 

650.25 

16581.375 

5-0497 

2-9434 

25.6 

80.425 

5H.72 

655-36 

16777.216 

5-0596 

2.9472 

25-7 

80.739 

518.75 

660.49 

16974.593 

5.0695 

2.9510 

25.8 

81.053 

522.79 

665.64 

17173.512 

5-0793 

2-9549 

25-9 

81.367 

526.85 

670.81 

17373.979 

5.0892 

2.9586 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   369 


CIRCLES,    SQUARES,    AND    CUBES— Continued. 


n 
Diam. 

»7T 

Circumf. 

IT 
*»- 

4 
Area. 

«' 
Square. 

«« 
Cube. 

^n        \n 
Sq.  Root.  :  Cub.  Rt. 

26.0 

81.681 

530-93 

676.00 

17576.000 

5.0990 

2.9624 

26.1 

81.996 

535-02 

68I.2I 

I7779-58I 

5.1088 

2.9662 

26.2 

82.310 

539.13 

686.44 

17984-728 

5.II85 

2.9701 

26.3 

82.624 

543-25 

691.69 

18191.447 

5.1283 

2.9738 

26.4 

82.938 

547-39 

696.96 

18399.744 

5.I2SO 

2.9776 

26.5 

83.252 

55L55 

702.25 

18609.625 

5.1478 

2.9814 

26.6 

83.566 

555.72 

707.56 

18821.096     5.1575 

2.9851 

26.7 

83.881 

559.90 

712.89 

19034.163     5.1672 

2.9888 

26.8 

84.195 

564-10 

718.24 

19248.832    f-1768 

2  .  9926 

26.9 

84.509 

568.32 

723-61 

19465  .  109 

5.1865 

2.9963 

27.0 

84-823 

572.56 

729.00 

19683.000 

5.1962 

3-0000 

27.1 

85-I37 

576.80 

734-41 

19902.511 

5-2057 

3-0037 

27.2 

85.451 

581.07 

739-84 

20123.648 

5-2153 

3.0074 

27-3 

85-765 

585.35 

745.29 

20346.417 

5.2249 

3.OIII 

27.4 

86.080 

589.65 

750.76 

20570.824 

5.2345 

3-0147 

27-5 

86.394 

593-96 

756.25 

2070.875 

5.2440 

3.0184 

27.6 

86.708 

598-29 

761.76 

21024.576 

5-2535 

3.0221 

27.7 

87.022 

602.63 

767.29 

21253-933 

5.2630  i  3.0257 

27.8 

87  336 

606.99 

772-84 

21484.952 

5.2725 

3.0293 

27.9 

87.650 

611.36 

778.41 

21717.639 

5.2820 

3-0330 

28.0 

87-965 

615-75 

784.00 

21952.000 

5.2915 

3.0366 

28.1 

88.279 

620.  16 

789.61 

22188.041 

5.3009 

3.0402 

28.2 

88.593 

624.58 

795-24 

2242^.768 

5-3103 

3-0438 

28.3 

88.907 

629.02 

800.89 

22  65.187 

5-3I97 

3-0474 

28.4 

89.221 

633-47 

806.56 

22906.304 

5.3291 

3.0510 

28.5 

89.535 

637-94 

812.25 

23149.125 

5.3385 

3.0546 

28.6 

89.850 

642.42 

817.96 

23393.656 

5.3478   3-058I 

28.7 

90  164 

646.93 

823.69 

23639.903 

5-3572 

3.0617 

28.8 

90.478 

651.44 

829.44 

23887.872      5.3665 

3.0652 

28.9 

90.792 

655.97 

835-21 

24137.569      5.3758 

3.0688 

29.0 

91.106* 

660.52 

841.00 

24389.000 

5.3852 

3.0723 

29.1 

91.420 

665.08 

846.81 

24642.171 

5-3944 

3.0758 

29.2 

91-735 

669.66 

852.64 

24897.088 

5.4037 

3-0794 

29-3 

92.049 

674.26 

858.49 

25153.757 

5.4129 

3-0829 

29.4 

92.363 

678.87 

864.36 

25412.184 

5-4221 

3.0864 

29  5 

92.677 

683.49 

870.25 

25672.375 

5-4313 

3-0899 

29.6 

92.991 

688.13 

876.16 

25934.336 

5-4405 

3-0934 

29.7 

93.305 

692.79 

882.09 

26198.073 

5-4497 

3.0968 

29.8 

93.619 

697.47 

888.04 

26463.592 

5.4589 

3-1003 

29.9 

93-934 

702.15 

894.01 

26730'.  899 

5.4680 

3-1038 

30.0 

94.248 

706.86 

900.00 

27000.000 

5-4772 

3-1072 

30.1 

94.562 

711.58 

906.01 

27270.901 

5.4863 

3.1107 

_30.2 

94.876 

716.32 

912.04 

27543.608 

5-4954 

3.1141 

37°  APPENDIX  CONTAINING  REFERENCES  AND  TABLES 
CIRCLES,    SQUARES,    AND    CUBES— Continued. 


n 
Diam. 

mr 
Circumf. 

77 

-4 

Area. 

ni 
Square. 

«3 

Cube. 

y~» 

Sq.  Root. 

3 

*u 

Cub.  Rt. 

30.3 

95.190 

721.07 

918.09 

27818.  127 

5  -  5045 

3.H76 

30.4 

95.505 

725-83 

924.16 

28094.464 

5-5I36 

3.I2IO 

30.5 

95.819 

730.62 

930.25 

28372.625 

5.5226 

3-1244 

30.6 

96.133 

735-42 

936.36 

28652.616 

5.5317 

3.1278 

30-7 

96.447 

•  740.23 

942.49 

28934.443 

5  .  5407 

3.I3I2 

30.8 

96.761 

745.06 

948  .  64 

292I8.II2 

5  •  5497 

3.1346 

30.9 

97-075 

749.91 

954.81 

29503.629 

5.5587 

3.1380 

31.0 

97.389 

754.77 

961.00 

297QI.OOO 

5-5678 

3.I4I4 

3I-I 

97.704 

759.65 

967.21 

30080.231 

5.5767 

3.1448 

31.2 

98.018 

764.54 

973-44 

30371.328 

5-5857 

3.I48I 

31-3 

98.332 

769.45 

979.69 

30664.297 

5.5946 

3.I5I5 

31-4 

98  .  646 

774-37 

985.96 

30959.144 

5-6035 

3.I548 

31-5 

98.960 

779-31 

992.25 

31255.875  • 

5-6124 

3.1582 

31.6 

99.274 

784.27 

998.56 

31554.496 

5.6213 

3-1615 

31-7 

99.588 

789.24 

1004.89 

31855.013 

5.6302 

3.1648 

31-8 

99.903 

794.23 

1011.24 

32157.432 

5.6391 

3.1681 

31-9 

100.22 

799-23 

1017-61 

32461.759 

5.6480 

3.1715 

32.0 

ioo.  S3 

804.25 

1024.00 

32768.000 

5-6569 

3.1748 

32.1 

100.85 

809.28 

1030.41 

33076.161 

5-6656 

3.1781 

32.2 

101.16 

814.33 

1036.84 

33386.248' 

5.6745 

3-1814 

32.3 

101.47 

819.40 

1043.29 

33698.267 

5-6833 

3-I847 

32-4 

101.79 

824.48 

1049.76 

34012.224 

5.6921 

3.1880 

32-5 

IO2.  IO 

829.58 

1056.25 

34328.125 

5-7008 

s-ig^ 

32.6 

102.42 

834-69 

1062.76 

34645.976 

5.7096 

3-1945 

32.7 

102.73 

839.82 

1069.29 

34965.783 

5.7183 

3.197* 

32.8 

103.04 

844.96 

1075-84 

35287.552 

5.7271 

3.2010 

32-9 

103  .  36 

850.12 

1082.41 

35611.289 

5.7358 

3.2043 

33'0 

103.67 

855.30 

1089.00 

35937.000 

5.7446 

3-2075 

33-1 

103.99 

860.49 

1095.61 

36264.691 

5.7532 

3.2108 

33-2 

104.30 

865.70 

1102.24 

36594.368 

5.7619 

3.2140 

33-3 

104.62 

870.92 

1108.89 

36926.037 

5-7706 

3.2172 

33-4 

104.93 

876.16 

1115.56 

37259.704 

5.7792 

3.2204 

33-5 

105.24 

881.41 

1122.25 

37595-375 

5.7S79 

3.2237 

33-6 

105  .  56 

886.68 

1128.96 

37933.056 

5.7965 

3.2269 

33-7 

105.87 

891.97 

1135-69 

38272.753 

5-8051 

3.2301 

33-8 

IO6.I9 

897.27 

1142.44 

38614.472 

5.8137 

3-2332 

33-9 

106.50 

902.59 

1149.21 

38958.219 

5-8223 

3.2364 

34-o 

106.81 

907-92 

1156.00 

39304.000 

5.8310 

3-2396 

34-1 

107.13 

913.27 

1162.81 

39651.821 

5.8395 

3.2428 

34-2 

107.44 

918.63 

1169.64 

40001  .688 

5  .  8480 

3.2460 

34-3 

107.76 

924.01 

1176.49 

40353.607 

5-8566 

3.2491 

34-4 

108.07 

929.41 

1183.36 

40707.584 

5-8651 

3-2522 

4PPENDIX  CONTAINING  REFERENCES  AND  TABLES.   37  r 
CIRCLES,    SQUARES,    AND   CUBES— Continued. 


n 
Diam. 

HIT 

Circumf. 

„.? 

Area. 

w2 
Square. 

«»          t'« 
Cube.      Sq.  Root. 

V» 
Cub.  Rt. 

34-5 

108.38 

934-82 

IigO.25 

41063.625 

5.8730 

3-2554 

34-6 

108.70 

940.25 

II97.:6 

41421.736 

5.8821 

3.2586 

34-7 

lOg.OI 

945.69 

1204.09 

41781.923 

5.8906 

3.2617 

3-4-8 

109-33 

951.15 

1211.04 

42144.192 

5.8991 

3  •  2648 

34-9 

109.64 

956.62 

I2I8.0I 

42508.549 

5.9076 

3-2679 

35-o 

109.96 

962.11 

1225.00 

42875.000 

5.9161 

3.2710 

35-1 

110.27 

967.62 

1232.01     43243.551 

5.9245 

3.2742 

35-2 

110.58 

973-14 

1239.04 

43614.208 

5.9329 

3-2773 

35-3 

IlO.gO 

978.68 

1246.09 

43986.977 

5-9413 

3  •  2804 

35-4 

III  .21 

984.23 

1253.16 

44361.864 

5-9497 

3-2835 

35-5 

"I-  53 

989  .  80 

1260.25 

44738.875 

5.9581 

3.2866 

35.6 

111.84 

995.38 

1267.36 

45118.016 

5.9665 

3-2897 

35-7 

112.15 

1000.98 

1274.49 

45499.293 

5-9749 

3-2927 

35-8 

112.47 

I006.60 

1281.64 

45882.712 

5.9833 

3-2958 

35-9 

112.78 

1012.23 

I288.8I 

46268.279 

5.9916 

3-2989 

36.0 

113.10 

1017-88 

1296.00 

46656  ooo 

6.0000 

3.3019 

36-1 

113.41 

1023.54 

1303.21 

47045.881 

6.0083 

3  •  3050 

36.2 

"3-73 

1020.22 

1310.44 

47437.928 

6.0166 

3-3080 

36.3 

114.04    1034.91 

1317.69 

47832.147 

6.0249 

3.3"i 

36.4 

114.35    1040.62 

I324-96 

48228.544 

6.0332 

3.3I4I 

39-5 

114.67 

1046.35 

1332.25 

48627.125 

6.0415 

3.3I7I 

36.6 

114.98    1052.09 

I339.56 

49027.896 

6.0497 

3-3202 

367 

115.30    1057.84 

1346.89 

49430.863 

6.0^80 

3-3232 

36.8 

115-61 

1063.62 

1354.24 

49836.032 

6.0663 

3-3262 

36.9 

115.92 

1069.41 

1361.61 

50243.409 

6-0745 

3.3292 

37-0 

116.24 

1075.21 

1369.00 

50653.000 

6.0827 

3-3322 

37-1 

"6.55 

loSi  .03 

1376.41 

51064.811 

6.0909 

3-3352 

37-2 

116.87 

1086.87 

1383.84 

51478.848  1  6.0991 

3-3382 

37-3 

117-18 

1092.72 

1391.29 

51895.117 

6.1073 

3-3412 

37-4 

117.50 

1098.58 

1398.76 

52313.624 

6.1155 

3-3442 

37-5 

117.81 

1104.47 

1406.25 

52734.375 

6.1237 

3.3472 

37-6 

118.12 

1110.36 

1413.76 

53157-376 

6.1318 

3-3501 

37.7 

118.44 

1116.28  i  1421.29 

53582.633 

6.1400 

3-3531 

37-8 

118.75 

1122.21 

1428.84 

54010.152 

6.1481 

3.350r 

37-9 

119.07 

1128.15 

1436.41 

54439.939 

6.1563 

3-3590 

38.0 

119-38 

II34-" 

1444.00 

54872.000 

6.1644 

3-3620 

38.1 

119.69  !  1140.09 

M5I.6I 

55306.341 

6.1725 

3  •  3649 

38.2 

120.01      1146.08 

1459.24 

55742.968 

6.1806 

3-3679 

38.3 

I2O.32     1152.09 

1466.89 

56181.887 

6.1887 

3.3703 

38.4 

120.64 

1158.12 

1474.56 

56623  .  104 

6.1967 

3-3737 

38-5 

120.95 

1164.16 

1482.25 

57066.625 

6  ,  2048 

3.376.7 

38.6 

121.27 

II7O.2I 

1489.96 

57512.456 

6.2129 

3.3796 

J>8.7 

121.58  '  1176.28 

1497.69 

57960.603 

6.2209 

3-3^25 

372  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 
CIRCLES,    SQUARES,    AND    CUBES— Continued. 


n 
Diam. 

W7T 

Circumf. 

"; 

Area. 

ni 
Square. 

n* 

Cube. 

VH 

Sq.  Root. 

3 

\'n 
Cub.  Rt. 

38.8 

121.89 

"82.37 

1505.44 

58411.072 

6.2289 

3.3854 

38.9 

122.21 

1188.47 

1513.21 

58863.869 

6.2370 

3-3883 

39.0 

122.52 

1194.59 

1521.00 

59319.000 

6.2450 

3-39^2 

39-i 

122.84 

1200.72 

I528.8I 

59776.471 

6.2530 

3.3941 

39-2 

123.15 

1206.87 

1536.64 

60236.288 

6.26lO 

3.3970 

39-3 

123.46 

1213.04 

1544.49 

60698.457 

6.2689 

3-3999 

39-4 

123.78 

1219.22 

1552.36 

61162.984 

6.2769 

3.4028 

39-5 

124.09 

1225.42 

1560.25 

61629.875 

6.2849 

3-4056 

39.6 

124.41 

1231.63 

1568.16 

62099.136 

6.2928 

3-4085 

39-7 

124.72 

1237.86 

1576.09 

62570.773 

6  .  3008 

3.4II4 

»J  7  ' 

39.8 

125.04 

1244.  10 

1584.04 

63044.792 

6.3087 

3.4142 

39-9 

125-35 

1250.36 

1592.01 

63521.199 

6.3166 

3.4I7I 

40.0 

125.66 

1256.64 

I6OO.OO 

64000  .  ooo 

6.3245 

3-4200 

40.1 

125.98 

1262.93 

1608.  oi 

64481.201 

6.3325 

3-4228 

40.2 

126.29 

1269.23 

1616.04 

64964.808 

6  .  3404 

3-4256 

40.3 

I26.6I 

1275.56 

1624.09 

65450.827 

6.3482 

3.4285 

40.4 

126-92 

1281.90 

1632.16 

65939.264 

6.3561 

3.4313 

40-5 

127.23 

1288.25 

1640.25 

66430.125 

6.3639 

3-4341 

40.6 

127-55 

1294.62 

1648.36 

66923.416 

6.3718 

3-4370 

40.7 

127.86 

I3OI.OO 

1656.49 

67419.143 

6.3796 

3-4398 

40.8 

I28.I8 

1307.41 

1664.64 

67911.312 

6.3875 

3.4426 

40.9 

128.49 

I3I3.82 

I672.8I 

68417.929 

6-3953 

3.4454 

41.0 

I28.8I 

1320.25 

1681.00 

68921.000 

6.4031 

3.4482 

41.1 

129.12 

1326.70 

1689.21 

69426.531 

6.4109 

3-4510 

41.2 

129.43 

1333.17 

1697.44 

69934.528 

6.4187 

3-4538 

4i-3 

129-75 

I339.65 

1705-69 

70444.997 

6.4265 

3.4566 

41.4 

130.06 

1346.14 

1713.96 

70957.944 

6-4343 

3-4594 

41-5 

130.38 

1352.65 

1722.25 

71473.375 

6.4421 

3.4622 

41.6 

130-69 

1359.  J8 

1730-56 

71991.296 

6.4498 

3-4650 

41.7 

131.00 

1365.72 

1738.89 

72511.713 

6-4575 

3-4677 

41.8 

I3L32 

1372  ,28 

1747.24 

73034.632 

6.4653 

3.4705 

41.9 

131.63 

1378-85 

I755.6i 

73560.059 

6.4730 

3-4733 

42.0 

I3L95 

1385.44 

1764.00 

74088.000 

6.4807 

3.4760 

42.1 

132.26 

1392.05 

1772.41 

74618.461 

6.4884 

3.4788 

42.2 

132.58 

1398.67 

1780.84 

75151.448   6.4961 

3-4815 

42.3 

132.89 

1405-31 

1789.29 

75686.967 

6.5038 

3.4843 

42.4 

133-20 

1411  .96 

1797.76 

76225.024 

6.5H5 

3.4870 

42.5 

I33.52 

1418.63 

1806.25 

76765.625 

6.5192 

3-4898 

42.6 

133.83 

1425-31 

1814.76 

77308.776 

6.5268 

3.4925 

42.7 

134.15 

1432.01 

1823.29 

77854.483 

6-5345 

3-4952 

42.8 

134.46 

1438.72 

1831.84 

78102.752 

6.5422 

3.4980 

42.9 

134-77 

1445.45 

1840.41 

78953.55*9 

6.5498 

3.5007 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   373 
CIRCLES,    SQUARES,    AND    CUBES—  Continued. 


n 
Diam. 

nir 

Circumf. 

"'; 

Area. 

«2 

Square. 

«3 

Cube. 

»'«         V« 

Sq.  Root.     Cub.  Rt. 

43-0 

I35-09 

1452.20 

1849.00 

79507.000 

6-5574 

3  •  5034 

43-1 

135-40 

1458.96 

1857.61 

80062.991 

6.5651 

3.<;o6i 

43-2 

135-72 

I465.74 

1866.24 

80621.568 

6.5727 

3.5088 

43-3 

136.03 

1472.54 

1874.89 

81182.737 

6  .  5803 

3.5II5 

43-4 

136.35 

1479.34 

1883.56 

81746.504 

6.5879 

3.5I42 

43-5 

136.66 

1486.17 

1892.25 

82312.875 

6-5954 

3.516-9 

43-6 

136.97 

1493-01 

1900.96 

82881.856 

6  .  6030 

3.5io6 

43-7 

137.29 

1499.87 

1909.69 

83453.453 

6.6ic6 

3.5223 

43-3 

137.60 

1506.74 

1918.44 

84027.672 

6.6182 

3.5250 

43-9 

I37-92 

1513-63 

1927.21 

84604.519 

6.6257 

3o277 

44.0 

138-23 

1520.53 

1936.00 

85184.000 

6.6333 

3o303 

44.1 

138.54 

I527.45 

1944.81 

85766.121 

6.6408 

3-5330 

44-2 

138.86 

1534-39 

1953  64 

86350.888 

6.6483 

3-5357 

44-3 

139-17 

I54r.34 

1962.49 

86938.307 

6.6558 

3.53S4 

44-4 

139-49 

1548.30 

1971-36 

87528.384 

6.6633 

3-5410 

44-5 

139-80 

1555-28 

1980.25 

88I2I.I25 

6.6708 

3-5437 

44.6 

140.  12 

1562.28 

1989.16 

88716.536 

6.6783 

3-5463 

44-7 

140.43 

1569-30 

1998.09 

89314.623 

6.6858 

3-5490 

44.8 

140.74 

1576.33 

2007.04 

89915.392 

6.6933 

3-55i6 

44-9 

141.06 

1583.37 

2OI6.OI 

90518.849 

6.7007 

3-5543 

45-0 

I4L37 

1590.43 

2025.00 

91125.000 

6.7082 

3.5569 

45-1 

141.69 

I597-5I 

2034.01 

91733.851 

6.7156 

3-5595 

45-2 

142.00 

1604.60 

2043-04      |      92345.408 

6.7231 

3-5621 

45-3 

142.31 

1611.71 

2052.09 

92959.677 

6-7305 

3-5648 

45-4 

142.63 

1618.83 

2061.  16 

93576.664 

6-7379 

3-5674 

45-5 

142.94 

1625.97 

2070.25 

94196.375 

6-7454 

3-5700 

45-6 

143  .  26 

1633.13 

2079.36 

94818.816 

6.7528 

3-5726 

45-7 

143-57 

1640.30 

2088.49 

95443  .  993 

6  .  7602 

3-5752 

45-3 

143.88 

1647.48 

2097.64 

96071.912 

6.7676 

3o778 

45-9 

144.20 

1654.68 

2106.81 

96702.579 

6-7749 

3-5305 

46.0 

144-51 

1661.90 

2116.00 

97336.000 

6.7823 

3-5330 

46.1 

144.83 

1669.14 

2125.21 

97972.181 

6.7897 

3.5356 

46.2 

145-14 

1676.39 

2134.44 

98611.128         6.7971 

3o332 

46.3 

145.46 

1683.65 

2143.69 

99252.847         6.8044 

3-5908 

46.4 

145-77 

1690.93 

2152.96 

99897.344 

6.8117 

3-5934 

46.5 

146.08 

1698  .  23 

2162.25 

100544.625 

6.8191 

3.5960 

46.6 

146.40 

1705.54 

2171.56 

101194.696 

6.8264 

3.5986 

46.7 

146.71 

1712.87 

2180.89 

101847.563 

6.8337 

3.6011 

46.8 

I47.03 

1720.21 

2190.24 

102503.232 

6.8410 

3-6037 

46.9 

147-34 

1727.57 

2199.61 

103161.709 

6.8484 

3.6063 

47.0 

M7.65 

1734-94 

2209.00 

103823.000 

6.8556 

3.6088 

47.1 

147-97 

1742.34 

2218.41 

104487.111          6.8629 

3  6114 

47.2 

148  .  28 

1749.74 

2227.84 

105154.048         6.8702 

3-6139 

374  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 
CIRCLES,    SQUARES,    AND   CUBES— Continued. 


n 
Diam. 

nir 
Circumf. 

+z 

4 
Area. 

11* 
Square. 

«3 

Cube. 

*5 

Sq.  Root. 

V; 

Cub.  Rt. 

47-3 

148  .  60 

I757.I6 

2237.29     105823.817 

6-8775 

3.6165 

47-4 

148.91 

1764.60 

2246  .76     I  06496  .  424 

6.8847 

3-6I90 

47-5 

149.23 

1772.05 

2256.25     107171.875 

6.8920 

3.6216 

47.6 

M9-54 

1779.52 

2265.76 

107850.  176 

6.8993 

3-6241 

47-7 

149.85 

1787.01 

2275.29 

108531.333 

6.9065 

3.6267 

47-8 

150.17 

1794-51 

2284.84 

109215.352 

6.9137 

3.6292 

47-9 

150.48 

1802.03 

2294.41 

109902.239 

6  .  9209 

3.6317 

48.0 

150.80 

1809.56 

2304.00 

IIO592.OOO 

6.9282 

3  •  6342 

48.1 

151  .11 

1817.11 

2313-61 

111284.641 

6-9354 

3-6368 

48.2 

151.42 

1824.67 

2323.24 

111980.168 

6.9426 

3.6303 

48.3 

I5L74 

1832.25 

2332.89 

112678.587 

6.9498 

3.6418 

48-4 

152.05 

1839.84 

2342.56 

II3379-904 

6.9570 

3.6443 

48.5 

152.37 

I847.45 

2352.25 

114084.125 

6  .  9642 

3.6468 

48.6 

152.68 

1855.08 

2361.96 

114791.256 

6.9714 

3.6493 

48.7 

153-00 

1862.72 

2371.69 

II550I.303 

6.9785 

3-6518 

48.8 

153.31 

1870.38 

2581.44 

116214.272 

6.9857 

3-6543 

48.9 

153.62 

1878.05 

2391.21 

116930.169 

6.9928 

3-6568 

49.0 

153-94 

1885.74 

2401  .OO 

117649.000 

7.0000 

3.6593 

49.1 

I54.25 

1893-45 

2410.81 

118370.771 

7.0071 

3.6618 

49.2 

154.57 

1901  .  17 

2420.64 

119095.488 

7-0143 

3  •  6643 

49-3 

154.88 

1908  .  90 

2430.49 

119823.157 

7.0214 

3.6668 

49-4 

I55-I9 

1916.65 

2440.36 

120553.784 

7.0285 

3.6692 

49-5 

155-51 

1924.42 

2450.25 

121287.375 

7-0356 

3-6717 

49.6 

155.82 

1932.21 

2460.16 

122023.936 

7  0427 

3-6742 

49-7 

156.14 

1940.00 

2470.09 

122763.473 

7  .  0498 

3-6767 

49-8 

156.45 

1947.82 

2480.04 

123505.992 

7.0569 

3.6791 

49-9 

156.77 

I955-65 

2490.01 

124251.499 

7  .  0640 

3.6816 

50.0 

157-08 

1963.50 

2500.00 

I25OOO.OOO 

7.0711 

3.6840 

51-0 

160.22 

2042  .  82 

2601.00 

132651.000 

7.1414 

3.7084 

52.0 

163.36 

2123.72 

2704.00 

140608.000 

7.2111 

3.7325 

53-o 

166.50 

2206.19 

2809  .  oo 

148877.000 

7.2801 

3-7563 

54-o 

169.64 

2290.22 

2916.00 

157464.000 

7.3485 

3.779S 

55-0 

172.78 

2375.83 

3025  .  oo 

166375.000 

7.4162 

3.8030 

56.0 

175-93 

2463.01 

3136.00 

I756l6.000 

7.4833 

3.8250 

57-0 

179.07 

255I-76 

3249.00 

185193.000 

7.5498 

3-8485 

58.0 

182.21 

2642.08 

3364.00 

I95II2.OCO 

7-6158 

3.8700 

59-o 

185.35 

2733-^7 

3481.00 

205379.000 

7.6811 

3.8930 

60.0 

188.49 

2827.44 

3600  .  oo 

2I6OOO.OOO 

7.746o 

3-9MC, 

61.0 

I9L63 

2922.47 

3721.00 

226981.000 

7.8102 

3.93fl5 

62.0 

194-77 

3019.07 

3844.00 

238328.  ooo 

7-8740 

3-957Q 

63.0 

197.92 

3II7.25 

3969  .  oo 

250047.000 

7-9373 

3.9791 

64.0 

2OI.O6 

3216.99 

4096  .  oo 

262144.000 

8  .  oooo 

4  .  oooo 

65.0 

204  .  20 

3318.31 

4225.00 

274625.000 

8.0623 

4.0207 

66.0 

207  .  34 

3421.20 

4356-00 

287496.000 

8.  1240 

4.0412 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   375 


CIRCLES,    SQUARES,   AND    CUBES—  Continued. 


n 
Diatn. 

WIT 

Circumf. 

«»-                         *a 
4 

Area.                Square. 

«» 

Cube. 

^       v« 

Sq.  Root,  !  Cub.  Rt. 

67.0 

210.48 

3525.66 

4489-00 

300763.000 

8.1854 

4.0615 

68.0 

213.63 

3631-69 

4624.00 

314432.000 

8.2462 

4-0817 

69.0 

216.77 

3739-29 

4761  .OO 

328509.000 

8.3066 

4.1016 

70.0 

219.91 

3848.46 

49OO.OO 

343000.000 

8.3666 

4.1213 

71.0 

223.05 

3959.20 

5041.00 

357911.000 

8.4261 

4.1408 

72.0 

226.19 

4071.51 

5184.00 

373248.000 

8.4853 

4  .  1602 

73-o 

229.33 

4185.39 

5329.00 

389017.000 

8.5440 

4.1793 

74.0 

232.47 

4300.85 

5476.00 

405224.000  i    8.6023 

4.1983 

75-o 

235.62 

4417.67 

5625.00 

421875.000 

8.6603 

4.2172 

76.0 

238.76 

4536.47 

5776.00 

438976.000 

8.7178 

4-2358 

77.0 

241.90 

4656.63 

5929  oo 

456533.000 

8.7750 

4-2543 

78.0 

245.04 

4778.37 

6084.00 

474552.000 

8.   318 

4-2727 

79.0 

248.18 

4901.68 

6241  .OO 

493039.000 

8.8S82 

4-2908 

80.0 

25L32 

5026.56 

64OO.OO 

512000.000 

8-9443 

4-3089 

81.0 

254-47 

5153.01 

6561.00 

531441.000 

9.0000 

4-3267 

82.0 

257.61 

5281.03 

6724.00 

551368.000 

9-0554 

4.3445 

83.0 

260.75 

5410.62 

6889.00 

571787.000 

9.1104 

4.3621 

84.0 

263  .  89 

554L78 

7056.00 

592704.000 

9.1652 

4-3795 

85.0 

267.03 

5674.50 

7225.00 

614125.000 

9.  -195      4-3968 

86.0 

270.17 

5808.81 

7396.00 

636056.000 

9.2736  :  4.4140 

87.0 

273.32 

5944.69 

7569.00 

658503.000 

9.3274  !  4.4310 

88.0 

276.46 

6082.13            7744.00 

681472.000 

9.3808 

4.4480 

89.0 

279.6C 

6221.13            792I.OO 

704969.000      9.4340 

4.4647 

90.0 

282.74 

6361.74            SlOO.OO 

729000.000 

9.4868 

4.4814 

91.0 

285.88 

6503.89      |      8281.00 

753571.000 

9-5394 

4-4979 

92.0 

289.02 

6647.62            8464.00 

778688.000 

9-59*7 

4-5144 

93-0 

292.17 

6792.92 

8649  .  oo 

804357.000 

9-6437 

4.5307 

94.0 

295.31 

6939.78 

8836.00 

830584.000 

9.6954 

4.5468 

95-0 

298.45             7088.23 

9025.00 

857375.000 

9.7468 

4.5629 

96.0 

301.59            7238.24 

9216.00 

884736.000 

9.7980 

4-5789 

97.0 

304.73             7389.83 

9409.00 

912673.000 

9.8489 

4-5947 

98.0 

307.87            7542.98 

9604.00 

941192.000 

9.8995 

4.6104 

99.0 

311.02 

7697-68 

9801  .00 

970299  .  ooo 

9-9499 

4.6261 

100.  0 

314.16 

7854.00 

10000.00 

lOOOOOO.OOO 

10.0000 

4.6416 

3/6  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 


TABLE  No.   IV. 

CIRCUMFERENCES   AND    AREAS   OF   CIRCLES.* 


Diam. 

Circum. 

Area. 

Diam. 

Circum. 

Area. 

Diam. 

Circum. 

Area. 

i 

3.1416 

0.7854 

65 

204  .  20 

33*8  3i 

129 

405-27 

13069.81 

2 

6.2832 

3.1416 

66 

207.34 

3421.19 

130 

408.41 

13273.23 

3 

9.4248 

7.0686 

67 

210.49 

3525-65 

I3I 

41  i  .55 

13478.22 

4 

12.5664 

12.5664 

68 

213.63 

3631.68 

132 

414.69 

13684.78 

5 

15.7080 

19-635 

69 

216.77 

3739-28 

133 

417-83 

13892.91 

6 

18.850 

28.274 

70 

219.91 

3848.45 

T34 

420.97 

14102.61 

7 

21.991 

38.485 

71 

223.05 

3959-19 

135 

424.12 

14313.88 

8 

25-133 

50.266 

72 

226.19 

4071.50 

136 

427.26 

14526.72 

9 

28.274 

63.617 

73 

229.34 

4185.39 

137 

430.40 

14741.14 

10 

31.416 

78-540 

74 

232.48 

4300.84 

138 

433-54 

14957.12 

II 

34-558 

95-033 

235-62 

4417.86 

436.68 

15174.68 

12 

37-699 

113.10 

76 

238.76 

4536.46 

140 

439.82 

15393.80 

Z3 

40.841 

1^2.73 

77 

241.90 

4656.63 

141 

442.96 

15614.50 

'4 

43.982 

153-94 

78 

245.04 

4778.36 

142 

446.11 

15836.77 

IS 

47.124 

176.71 

79 

248.19 

4901.67 

143 

449-25 

16060.61 

16 

50.265 

201.06 

80 

251-33 

5026.55 

144 

452.39 

16286.02 

*7 

53-407 

226.98 

81 

254.47 

5i53-oO 

MS 

455-53 

16513.00 

18 

56-549 

254.47 

82 

257.61 

5281.02 

146 

458.67 

16741.55 

19 

59.690 

283.53 

83 

260.75 

5410.61 

147 

461.81 

16971.67 

20 

21 
22 

62.832 

65-973 
69.115 

314.16 
346.36 
380.13 

84 

ii 

263.89 
267.04 
270.18 

5541-77 
5674-5° 
5808.80 

148 
149 
150 

464.96 
468.10 
471.24 

17203.36 
17436.62 
17671.46 

23 

72.257 

415-48 

87 

273-32 

5944-68 

151 

474-38 

17907.86 

24 

75-398 

452.39 

88 

276.46 

6082.12 

152 

477-52 

18145.84 

25 

78.540 

490.87 

89 

279.60 

6221  .14 

480.66 

18385.39 

26 

81.681 

530.93 

90 

282.74 

6361.73 

154 

483-81 

18626.50 

27 

84.823 

572.56 

gi 

285.88 

6503.88 

i55 

486.95 

18869.19 

28 

87.965 

92 

2*9-03 

6647.61 

156 

490.09 

19113.45 

29 

91.106 

660.52 

93 

292.17 

6792.91 

157 

493-23 

19359.28 

30 

94.248 

706.86 

94 

295-31 

6939.78 

158 

496.37 

19606.68 

31 
32 

97-3.89 
100.53 

754-77 
804.25 

95 
96 

298.45 
301-59 

7088.22 
7238.23 

159 
160 

499-51 
502  65 

19855-65 
20106.19 

33 

103.67 

855-30 

97 

304.73 

7389.81 

161 

505-80 

20358.31 

34 

106.81 

907.92 

98 

307-88 

7542.96 

162 

508.94 

20611.99 

109  .  96 

962.11 

99 

311.02 

7697-69 

163 

512.08 

20867.24 

36 

113.  10 

1017.88 

100 

314.16 

7853.98 

164 

515.22 

21124.07 

37 

116.24 

1075.21 

IOI 

3I7-30 

8011.85 

165 

518.36 

21382.46 

38 

119-38 

1134.11 

IO2 

320.44 

8171.28 

1  66 

521.50 

^1642.43 

a 

122.52 
125.66 

1194.59 
1256.64 

103 
104 

323-58 
326.73 

8332.29 
8494.87 

167 
1  68 

524  65 
527.79 

21903.97 
22167.08 

41 

128.81 

1320.25 

105 

329-87 

8659.01 

169 

530.93 

22431.76 

42 

131.95 

1385.44 

106 

333-01 

8824.73 

170 

534  07 

22698.01 

43 

1^5.09 

1452.20 

107 

336.15 

8992  .  02 

171 

537-21 

22965.83 

44 

138-23 

1520.53 

108 

339-29 

9100.88 

172 

540.35 

23235.22 

45 

Mi-37 

1590.43 

109 

342-43 

933L32 

543-50 

23506.  18 

46 

I44-5I 

1661  .90 

110 

345-58 

9503  •  S2 

T74 

546.64 

23778.71 

47 

147-65 

1734-94 

ii  i 

348.72 

9676.89 

24052.82 

48 

150.80 

1809.56 

112 

351.86 

9852.03 

176 

552.92 

24328  49 

153-94 

1885.74 

"3 

355-oo 

10028.75 

177 

556.06 

24605.74 

50 

157-08 

1963.50 

114 

358.14 

IO2O7.O3 

178 

559.20 

24884.56 

52 

160.22 
163.36 

2042  .  82 
2123.72 

"5 
116 

361.28 
364-42 

10386.89 
10568.32 

179 
180 

562.35 
565-49 

25164.94 
25446.90 

53 

166.50 

2206.18 

117 

367.57 

10751.32 

181 

568.63 

25730-43 

54 

169.65 

2290.22 

118 

370.71 

10935.88 

182 

571-  77 

26015.53 

55 

172.79 

3375.83 

119 

373-85 

III22.O2 

183 

574-91 

26302  .  20 

56 

I75.93 

2463.01 

120 

376.99 

11309.73 

184 

578-05 

26590.44 

179.07 
182.21 

2551.76 
2642.08 

121 
122 

380.13 
383  27 

11499.01 
11689.87 

185 
186 

581.19 
584-34 

26880.25 
27171.63 

59 

185  35 

2733-97 

I23 

386.42 

Il882.29 

187 

587.48 

27464.59 

60 

188.50 

2827.43 

124 

389-56 

12076.28 

1  88 

590.62 

27759.11 

61 

191.64 

2922.47 

I25 

392.70 

12271.85 

189 

593-76 

28055.21 

62 

194.78 

3019.07 

126 

395-84 

12468.98 

190 

596.90 

28352.87 

63 

197.92 

3117.25 

127 

398.98 

12667.69 

191 

600.04 

28652.11 

64 

2OI  .06 

3216.99 

128 

402.12 

12867.96 

192 

603.19 

28952.92 

*  From  Kent's  Pocket-book  for  Mechanical  Engineers. 


APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   37? 

TABLE  No.  V. 

LOGARITHMS   OF   NUMBERS. 


No, 

0 

1 

2 

3 

4 

5 

6 

7 

8 

5 

10 

oooo 

0043 

0086 

0128 

0170 

O2I2 

0253 

0294 

°334 

0374 

ii 

12 

0414 
0792 

0453 
0828 

0492 
0864 

0899 

0569 
0934 

0607 
0969 

0645 
1004 

0682 
1038 

0719 
1072 

0755 

1106 

13 

"39 

'"73 

1206 

1239 

1271 

'303 

1335 

1367 

1399 

'43° 

14 

1461 

1492 

1523 

1553 

1584 

1614 

1644 

1673 

1732 

15 

/i  76  1 

1790 

i8i8 

1847 

1875 

1903 

1931 

1959 

1987 

2014 

16 

2041 

2068 

2095 

2122 

2148 

2175 

2201 

2227 

2253 

2279 

jjy 

2304 

233° 

2355 

2380 

2405 

2430 

2455 

2480 

2504 

2529 

18 

2553 

2577 

2601 

2625 

2648 

2672 

2695 

2718 

2742 

2765 

19 

2788 

2810 

2833 

2856 

2878 

2900 

2923 

2945 

2967 

2989 

2O 

3010 

3032 

3054 

3075 

3096 

3"8 

3139 

3160 

3181 

3201 

21 

3222 

3243 

3263 

3284 

3304 

3324 

3345 

3365 

3385 

3404 

22 

3424 

3444 

3464 

3483 

3502 

3522 

3541 

3560 

3579 

3598 

23 

3617 

3636 

3655 

3674 

3692 

37" 

3729 

3747 

3/66 

3784 

24 

3802 

3820 

3838 

3856 

3874 

3892 

3909 

3927 

3945 

3962 

25 
26 

3979 
415° 

3997 
4166 

4014 
4183 

4031 
42<OO 

4048 
4216 

4065 
4232 

4082 
4249 

4099 
4265 

4116 
4281 

4U3 
4298 

27 

43H 

4330 

4346 

4362 

4378 

4393 

4409 

4425 

4440 

4456 

28 

4472 

4487 

4502 

45^ 

4533 

4548 

4564 

4579 

4594 

4609 

29 

4624 

4639 

4654 

4669 

4683 

4698 

47J3 

4728 

4742 

4757 

30 

4771 

4786 

4800 

4814 

4829 

"4843 

4857 

4871 

4886 

4900 

31 

4914 

4928 

4942 

4955 

4969 

4983 

4997 

5011 

5024 

5038 

32 

50|i 

5065 

5079 

5092 

5105 

5"9 

5'32 

5M5 

5*59 

5^2 

33 

5*98 

52" 

5224 

5237 

525° 

5263 

5276 

5289 

5302 

34 

53^5 

5328 

5340 

5353 

5366 

5378 

5391 

5403 

54*6 

5428 

35 

544i 

5453 

5465 

5478 

5490 

55°2 

55H 

5527 

5539 

5551 

36 

5563 

5575 

5587 

5599 

5611 

5623 

.5635 

5647 

5658 

5670 

37 

5682 

5694 

5705 

5717 

5729 

5740 

5752 

5763 

5775 

5786 

38 
39 

5798 
59" 

5809 
5922 

5821 
5933 

5832 
5944 

5843 
5955 

5855 
5966 

5866 
5977 

5877 
5988 

5888 
5999 

5899 
6010 

40 

6021 

6031 

6042 

6053 

6064 

6075 

6085 

6096 

6107 

6117 

6128 

6138 

6149 

6160 

6170 

6180 

6191 

6201 

6212 

6222 

42 

6232 

6243 

6253 

6263 

6274 

6284 

6294 

6304 

6314 

6325 

43 

6335 

6345 

6355 

6365 

6375 

6385 

6395 

6405 

6415 

6425 

44 

6435 

6444 

6454 

6464 

6474 

6484 

6493 

6503 

6513 

16522 

45 

653? 

6542 

655  ' 

6561 

6571 

6580 

6590 

6599 

6609 

6618 

46 

6628 

6637 

6646 

6656 

6665 

6675 

6684 

6693 

6702 

6712 

47 

6721 

6730 

6739 

6749 

6758 

6767 

6776 

6785 

6794 

6803 

48 

6812 

6821 

6830 

6839 

6848 

6857 

6866 

6875 

6884 

6893 

49 

6902 

6911 

6920 

6928 

6937 

6946 

6955 

6964 

6972 

6981 

50 

6990 

6998 

7007 

7016 

7024 

7033 

7042 

7050 

70591 

7067 

51 

7076 

7084 

7°93 

7101 

7110 

7118 

7126 

7'35 

7*43 

7152 

52 

7160 

7168 

7177 

7185 

7193 

7^202 

7210 

7218 

7226 

7235 

53 

7243 

7251 

7259 

7267 

7275 

7284 

7292 

7300 

7308 

7316 

54 

7324 

7332 

7340 

7348 

7356 

7364 

7372 

738o 

7388 

7396 

No. 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 


LOGARITHMS  OF  NUMBERS—  Continued. 


No, 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

55 

7404 

7412 

7419 

7427 

7435 

7443 

745  ' 

7459 

7466 

7474 

56 

7482 

7490 

7497 

75°5 

7513 

7520 

7528 

7536 

7543 

7551 

57 

7559 

7566 

7574 

7582 

7589 

7597 

7604 

7612 

-7619 

7627 

58 

7634 

7642 

7649 

7657 

7664 

7672 

7679 

7686 

7694 

7701 

59 

7709 

7716 

7723 

7738 

7745 

7752 

7760 

7767 

7774 

60 

7782 

7789 

7796 

7803 

7810 

7818 

7825 

7832 

7839 

7846 

61 

7853 

7860 

7868 

7875 

7882 

7889 

7896 

7903 

7910 

7917 

62 
63 

7924 
7993 

793i 
8000 

7938 
8007 

7945 
8014 

7952 
8021. 

7959 
8028 

7966 
8035 

7973 
8041 

7980 
8048 

7987 
8055 

64 

8062 

8069 

8075 

8082 

8089 

8096 

8102 

8109 

8116 

8122 

65 

8129 

8136 

8142 

8149 

8156 

8162 

8169 

8176 

8182 

8189 

66 

8195 

8202 

8209 

8215 

8222 

8228 

8235 

8241 

8248 

8254 

67 

8261 

8267 

8274 

8280 

8287 

8293. 

,8299 

8306 

8312 

8319 

68 
69 

8325 
8388 

8331 
8395 

8338 
8401 

8344 
8407 

8351 
8414 

8357 
8420 

8363 
8426 

8370 
8432 

8376 
8439 

838-2 
8445 

70 

8451 

8457 

8463 

8470. 

8476 

8482 

8488 

8494 

8500 

8506 

71 

8513 

8519 

8525 

8531 

8537 

8543 

8549 

8555 

8561 

8567 

72 

8573 

8579 

8585 

8591 

8597 

8603 

8609 

8615 

8621 

8627 

73 

8633 

8639- 

8645 

8651 

8657 

8663 

8669 

8675 

8681 

8686 

74 

8692 

8698 

8704 

8710 

8716 

8722 

8727 

8733 

^739 

8745 

75 

8751 

8756 

8762 

8768 

8774 

8779 

8785 

8791 

8797 

8802 

76 

8808 

8814 

8820 

8825 

8831 

8837 

8842 

8848 

8854 

8859 

77 

8865 

8871 

8876 

8882 

8887 

8893 

8899 

8904 

8910 

8915 

78 

8921 

8927 

8932 

8938 

8943 

8949 

8954 

8960 

8965 

8971 

79 

8976 

8982 

8987 

8993 

8998 

9004 

9009 

9015' 

9020 

9025 

80 

9031 

9036 

9042 

9047 

9053 

9058 

9063 

9069 

9074 

9079 

81 

9085 

9090 

9096 

9101 

9106 

9112 

9117. 

9122 

9128 

9U3 

82 

9138 

9H3 

9149 

9154 

9159 

9165 

9170 

9175 

9180 

9186 

83 

9191 

9196 

9201 

9206 

9212 

9217 

9222 

9227 

9232 

9238 

9243 

9248 

9253 

9258 

9263 

9269 

9274 

9279 

9284 

9289 

85 

9294 

9299 

9304 

9309 

93*5 

9320 

9325^ 

^9330 

9335 

9340 

86 

9345 

935° 

9355 

9360 

9365 

937° 

9375 

9380 

9385 

9390 

87 

9395 

9400 

9405 

9410 

94I5 

9420 

9425 

9430 

9435 

9440 

88 

9445 

945° 

9455 

9460 

9465 

9469 

9474 

9479 

9484 

9489 

8S 

9494 

9499 

9$P4 

9509: 

9513 

95*8 

9523 

9528 

9533 

9538 

go 

9542 

"9547 

9552 

9557 

9562 

9566 

9571 

9576 

9581 

9586 

9590 

9595 

9600 

9605 

9609 

9614 

9619 

9624 

9628 

9633 

92 

9638 

9643 

9647 

9652 

9657 

9661 

9666 

9671 

9675 

9680 

93 

9685 

9689 

9694 

9699 

97°3 

9708 

97*3 

9717 

9722 

9727 

94 

9731 

9736 

9741 

9745 

975° 

9754 

9759 

9763 

9768 

9773 

95 

9777 

9782 

9786 

979i 

9795 

9800 

9805 

9809 

9814 

9818 

96 

9823 

9827 

9832 

9836 

9841 

9845 

9850 

9854 

9859 

9863 

97 

9868 

9872 

9877 

9881 

9886 

9890 

9894 

.9899 

9903 

9908 

98 

9912 

9917 

9921 

9926 

9930 

9934 

9939 

9943 

9948 

9952 

99 

9956 

9961 

9965 

9969 

9974 

9978 

9983 

9987 

9991 

9996 

No, 

O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES.  379 

TABLE  ,  No.  VI. 

IMPORTANT   PROPERTIES   OF    FAMILIAR   SUBSTANCES. 


Specific 
Gravity. 
Water,  i. 

Specific 
Heat. 
Water,  i. 

Absorbing 
and  Radiat- 
ing Power  of 
Bodies  in 
Units  of  Heat 
per  Square 
Foot  for  Dif- 
ference of  i°. 

Conducting 
Power  in 
Units  oi  Heat 
_per  Square 
Foot  of  Sur- 
face with 
Difference 
of  i°. 

Weight 
in 
Pounds 

Melting 
Points. 
Degrees 
Fahr. 

Meta\s  from  32°  to  212°— 
Aluminium  

2  61  102.65 
6.  712 

I:!33 

8.788 
7-5 

7-744 
19-258 
11.352 

I3-598 
8.800 
16.000 
10.474 
7-834 
7.291 
7.191 

2.784 
3-I56 
2.240 
2.686 
2.650 

.86 
•  55 

•44 
1-43 

I.  00 

2.89 
2.03 

:i> 

.0006 
87 
i  .000 

.922 

.00122 
.00127 
.000089 
.00198 

.212 

.0508 
.0308 
•0939 
.092 
.1298 
.1138 
•0324 
•0314 
•0333 
.1086 
.0324 
.056 
.1165 
.0562 
•0953 

.2149 
.2174 
.2 

.2694 
-2I58 

•57 
•65 

.2415 
.2411 
-203 
.1977 
.2026 

.6588 

:fi, 

.416 

1.  000 

.504 

.238 
.2412 
3.2936 

.2210 

Per 
cu.  in. 

0.0956 
0.2428 
o-3533 
0.2930 
0.3179 
0.2707 
0.2801 
0.6965 
0.4106 
0.4918 
0.3183 
0-5787 
0.3788 
0.2916 
0.2637 
0.26 
Per 
cu.  ft. 
174.0 
197.0 
140.0 
168.0 
165.0 

IX 
I* 

62.5 
180.7 
127.0 

57-5 
55-o 
.050 
54-37 
62.35 

57-5 

.0807 
.0892 
.00559 
.1234 

810 
476 
1692 
1996 
2250 
!37oo 
2590 
608 

~39 
3700 

2OOO 
4000 
446 
680 

Antimony  

Bismuth  
Brass  

.049 
.0327 
.648 
.566 

.1329 

5i5-o 
103.0 
103.0 

Copper  . 

Iron,  cast  

Iron,  wrought  
Gold                ..  . 

Lead  
Mercury  at  32°  
Nickel 

50.0 



Platinum  

Silver. 

.0265 

Steel  ,  
Tin 

•0439 
.049 

.6786 
•735 
•735 
•735 
•735 

•73 
•73 

IO2.O 

Zinc 

Stones- 
Chalk  

Limestone 

Masonry  

Marble,  gray  
Marble,  white  

Woods- 
Oak 

5-6 
4-4 

0.4 
•»7 

Pine  white 

Mineral  substances- 
Charcoal,  pine 

Coal,  anthracite  
Coke  



Glass,  white    .. 

•5948 

!-S 

Liquids  — 
Alcohol,  mean  
Oil,  petroleum  
Steam  at  212°  
Turpentine  

1.480 
1.0853 



Water  at  62°.  .  . 

Solid— 
Ice  at  32° 

Gases- 
Air  at  32°  

Oxygen  
Hydrogen  

38G  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 


TABLE   No.  VII. 

COEFFICIENTS,    STRENGTH    OF   MATERIALS. 


Ultimate  Strength. 
Tons  per  Square  Inch. 

Moduli. 
Tons  per  Sq.  Inch. 

Tension. 

Com- 
pression. 

Shearing. 

Elasticity. 

Rig. 

T 

c 

s 

E 

Es 

54-io4 
7 
14 
15-20 

27-29 
24 

22 

IQ 

27-29 
25 
19-24 
25-50 

26-32 

30-45 
40-65 

So 
72 
70 
150 

10-14 

15-16 
28 
8-13 

22 
11-23 
15-26 

2-3 

7-IO 
2 
0.9 

3-7 
ii-34 
4 
4-7      . 
4-6 
4-7 

25-65 
42 

36-58 

60-75 

20 

35 
5 

3 
4 

24 

2-4 

34 

24-5 

14-24 
14-3 

i-6 

9-13 
II 

-  18-22 

]    « 

a 

-   $ 

M 

o" 

3 
10-14 

I 

4 

5000 

\        t0 
6000 

112,000 
to 

13,000 

12,000 

\        t0 

j     13,000 

I3,OOO 
7000 

8000 
5500 
6400 
45OO-6OOO 
6OOO 

5500 
IOOO 

800 

600 
950 

750 

650 

1300 
to 
2500 

5000 

5000 
to 

5200 

2800 
1500 

22OO 
I700- 
2400. 

Repeatedly  melted     .  .  •   ... 

Wrought-iron  — 
Finest  Low-  j  with    grain., 
moor  plates:  \  across    "     .. 

Bridge-iron:]^    ".    » 
Bars  finest            

Bars   soft  Swedish               .  . 

Wire             

Steel— 
Mild-*teel  plates                 « 

Axle  and  rail  steel  

Tungsten            "                 .  • 

Steel  wire.      .      

Piano-  wire.  

Copper  — 
Cast  

Rolled       

^Vire  hard  drawn 

Brass 

Wire      

Phosphor  bronze              

.Zinc    cast     

Zinc,  rolled  

Tin                     .              

Lead        

Timber- 
Oak                        

Pitch-pine                        . 

Ash..  

Beech  

Mahogany     

Stone  — 

Sandstone      

Brick  

From  Vol.  XXII. ,  Encyc.  Britannica. 


APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   381 

TABLE   No.  VIII. 

PROPERTIES    OF   AIR. 

OF  THE  WEIGHTS  OF  AIR,  VAPOR  OF  WATER,  AND   SATURATED    MIXTURES 
OF  AIR  AND  VAPOR  OF  DIFFERENT  TEMPERATURES,  UNDER   THE  ORDI- 
NARY ATMOSPHERIC  PRESSURE  OF  29.921  INCHES  OF  MERCURY. 


=5-  § 

5i 

.St* 

6 

!~ 

Mixtures  of  Air  saturated  with  Vapor. 

•~ 

u  *"  C 

u  u  3 

S& 

!x* 

*>>  4)  O 

"'•5  c 

•^  3 
««  W 

Elastic       Weight  of  a  cubic  foot  of  the  mixture. 

£ 

rt  *j  "" 

<uS 

Force  of  the 

3 
*2 

S  «.. 

<«  rt  <G 

^"o 

Air  in  the    | 

flj 
I 

E 

111 

|Q| 

pl 

mixture  of     Weight  of 
Air  and  Va-      th(f  Air 
por  in  inches          in 
of   Mercury.     pounds 

Weight  of 
the  Vapor 
in 
pounds. 

Total 
weight  of 
mixture 
in   pounds. 

1 

2 

3 

4 

5 

678 

0° 

•935 

.0864 

0.044 

29.877 

.0863 

.000079 

.086379 

12 

.960 

.0842 

.074 

29.849 

.0840 

.000130 

.084130 

22 

.980 

.0824 

.118 

29.803 

.0821 

.000202 

.082302 

32 

.000 

.0807 

.181 

29.740 

.0802 

.000304 

.080504 

42 

.020 

.0791 

.267 

29.654 

.0784 

.000440 

.078840 

52 

.041 

.0776 

.388 

29-533 

.0766 

.000627 

.077227 

60 

.057 

.0764 

.522 

29.399 

•0751 

.000830 

.075252 

62 

.061 

.0761 

.556 

•0/47 

.000881 

.075581 

70 

.078 

•075€l 

•754 

29.182 

.0731 

,001153 

.073509 

72 

082 

.0747 

.785 

29.136 

.0727 

.001221 

.073921 

82 

.102 

•0733 

1.092 

28.829 

.0706 

.OOI667 

.072267 

92 

.122 

.0720 

1.50* 

28.420 

.0684 

.002250 

.070717 

ICO 

•139 

.0710 

1.929 

27.992 

.0664 

.002848 

.069261 

102 

•143 

.0707 

2  036 

27-885 

.0659 

.002997 

.068897 

112 

.163 

.0694 

2.731 

27.190 

.0631 

-003946 

.067042 

122 

I84 

.0682 

3.621 

26.300 

•0599 

.005142 

.065046 

152 

.204 

.0671 

4.752 

25.169 

.0564 

.006639 

.063039 

142 

.224 

.0660 

6.165 

23.756 

.0524 

.008473 

.060873 

152 

•245 

.0649 

7-930 

21.991 

•0477 

.010716 

.058416 

162 

.265 

.0638 

10.099 

19.822 

.0423 

.013415 

.055715 

1/2 

.285 

.0628 

12.758 

17-163 

.0360 

.016682 

.052682 

182 

.306 

.0618 

15.960 

I3-96I 

.0288 

.020536 

.049336 

192 

.326 

.0609 

19.828 

10.093 

.0205 

.025142 

.045642 

2O2 

•347 

.0600 

24.450 

5-471 

.0109 

.030545 

.C4I-I45 

212 

.367 

.0591 

29.921 

o.ooo 

.0000 

.036820 

.036820 

382  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 

TABLE    No.  Mill.— Continued. 

PROPERTIES   OF   AIR. 


Mixture  of  Air  satu- 

ss^ 

U    U 

«-a 

jsta 

•—    a; 

rated  with  Vapor. 

Its 

If 

11 

«j  a 

<  0. 
—  v 

u 
JE 

rt 

fe 

OJ 

I1 

g| 

s 

Ps 

-I 

3-C 

u 

«*-  °  <" 

o 

S°  S3 

*j  c 

C/5  C 

3 

£« 

Q£ 

lit 

l|^ 

T,  ° 

0 

*o  ^ 

^l 

4>  C   3 

p  o  S 

D«l 

I,  ' 

"*"£'' 

a 

fa 

Is 

"3   C   U 

•§oa 

H  at  w 

"  UT3 

^1< 

•-  rt"' 

|1S 

H 

at 

u 

P3 

n 

U 

u 

1 

9 

10 

1  1 

12 

13 

14 

15 

0° 

.00092 

1092.4 

• 

.02056 

.02054 

48.5 

48.7 

12 

.00115 

646.1 

.... 

.02004 

.02006 

50.1 

50.0 

22 

.00245 

406.4 

.... 

.01961 

.01963 

51-0 

32 

.00379 

263.81 

3289 

.01921 

.01924 

52.0 

51-8 

42 

.00561 

178.18 

2252 

.01882 

.01884 

53-2 

52.8 

52 

.  008  i  9 

122.17 

J595 

.01847 

.01848 

54-0 

53-8 

60 

.01251 

92.27 

1227 

.01818 

.01822 

55-0 

54-9 

62 

.01179 

84-79 

.01811 

.01812 

56.2 

55-7 

70 

.01780 

64.59 

882 

.01777 

.01794 

57-3 

56-5 

72 

.01680 

59-54 

819 

.01777 

.01790 

58.5 

56.8 

82 

.02361 

42.35 

600 

.01744 

.01770 

57-2 

56.5 

92 

.03289 

30.40 

444 

.01710 

.01751 

58.5 

57-1 

TOO 

•04495 

23.66 

356 

.01690 

•01735 

59-  1 

57-8 

102 

•04547 

21.98 

334 

.01682 

.01731 

59-5 

57-8 

112 

.06253 

15-99 

253 

.01651 

.01711 

60.6 

58.5 

122 

.08584 

11.65 

194 

.01623 

.01691 

61.7 

59-  * 

132 

.11771 

8.49 

.01596 

.01670 

62.5 

59-9 

142 

.  16170 

6.18 

118 

.01571 

.01652 

63.7 

60.6 

152 

.22465 

4-45 

93-3 

•01544 

.01654 

65.0 

60.  5 

162 

.31713 

3.15 

74-5 

.01518 

.01656 

62.2 

60.4 

172 

•46338 

2.16 

59-2 

.01494 

.01658 

67.1 

60.  3 

182 

.71300 

1.402 

48.6 

.01471 

.01687 

68.0 

59'  5 

192 

1.22643 

.815 

39-8 

.01449 

68.9 

.... 

202 

2.80230 

•357 

32.7 

.01466 

.... 

68.5 

...» 

212 

Infinite 

.000 

27.1 

.01406 



71.4 



APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   383 


TABLE  No.  IX. 

MOISTURE  ABSORBED   BY  AIR. 

THE  QUANTITY  OF  WATER  WHICH  AIR  is  CAPABLE  OF  ABSORBING  TO  THE 

POINT  OF  MAXIMUM  SATURATION,  IN  GRAINS  PER  CUBIC  FOOT 

FOR  VARIOUS  TEMPERATURES. 


Degrees 

Fahr. 

Grains  in  a 
Cubic  Foot. 

Degrees 
Fahr. 

Grains  in  a 
Cubic  Foot. 

IO 

I  .  I 

85 

12.43 

15 

I-3I 

90 

14.38 

2O 

1.56 

95 

16.60 

25 

1.85 

100 

19.12 

30 

2.19 

105 

22.0 

32 

2-35 

no 

25-5 

35 

2-59 

115 

3O.O 

40 

3.06 

130 

42-5 

45 

3.6! 

141 

58.0 

50 

4.24 

157 

85.0 

55 

4-97 

170 

112.  5 

60 

5-82 

179 

138.0 

65 

6.81 

1  88 

166.0 

70 

7-94 

195 

194.0 

75 

9.24 

212 

265.0 

80 

10.73 

TABLE  No.  X. 

RELATIVE   HUMIDITY  OF  THE  AIR. 


Difference  of 
Temperature  of 
the  Air  and 
Dew-point. 

Temperature 
of  Air. 
32°  Fahr. 

Temperature 
of  Air. 
70°  Fahr. 

Temperature 
of  Air. 
95°  Fahr. 

O 

IOO 

IOO 

IOO 

I 

96 

97 

97 

2 

92 

93 

94 

3 

88 

90 

91 

4 

85 

87 

88 

5 

81      - 

84 

86 

6 

78 

81 

83 

7 

74 

78 

80 

8 

7i 

76 

78 

9 

68 

73 

75 

10 

65 

7T 

73 

12 

60 

66 

68 

14 

54 

61 

64 

16 

50 

57 

60 

18 

45 

53 

56 

20 

41 

49 

53 

22 

38 

46 

49 

24 

34 

43 

46 

384  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 


TABLE  No.  XL 

PROPERTIES   OF   SATURATED   STEAM. 
[From  Charles  T.  Porter's  treatise  on  The  Richards  Steam-engine  Indicator^ 


Press- 
ure 
above 

zero. 

Temperature. 

Sensible  Heat 
above 
zero  Fahr. 

Latent  Heat. 

Total  Heat 
above 
zero  Fahr. 

Weight  of 
One  Cubic 
Foot. 

Lbs.  per 

sq.  in. 

Fahr.  Deg. 

B.T.U. 

B.T.U. 

B.T.U. 

Lbs. 

1 

102.00 

102.08 

1042.96 

1145.05 

.0030 

2 

126.26 

126.44 

i.026.01 

1152.45 

.0058 

i8 

141.62 

141.87 

1015.25 

1157.13 

.0085 

4 

153.07 

153.39 

1007.22 

1160.63 

.Oil? 

5 

162.33 

162.72 

1000.72 

1163.44 

.01  37' 

6 

170.12 

170.57 

995.24 

1165.82 

:0163 

7 

176.91 

177.42 

990  47 

1167.89 

.0189 

8 

1$2.91 

183.48 

986.24 

1169.72 

.0^14 

9 

188.31 

188.94 

982.43 

1171.37 

.0239 

10 

193.24 

193.91 

978.95 

1172.87 

.0264. 

11 

197.76 

198.49 

975.76 

1174.25 

.0289 

12 

201.96 

202.73 

972.80 

1175.53 

.0313 

13 

205.88 

206.70 

970.02 

1176.73 

.0337 

\\ 

209.56 
213.02 

210.42 
213.93 

967.42 
964.97 

1177.85 
1178.91 

.036,3 
.0387 

16 

216  29 

217.25 

962.65 

1179.90 

.0413 

17 

219.41 

220.40 

960.45 

1180.85 

.0437 

18 

222.37 

223.41 

958.34 

1181.76 

.0462 

19 

225.  2a 

226.28 

956.34 

1182.62 

.0487 

20 

227.91 

229.03 

954.41 

1183.45 

.0511 

J31 

230.51 

231.67 

952.57 

1184.24 

.0536 

22 

233.01 

234.21 

950.79 

1185%  00 

.0561 

23 

2S5.43 

236.67 

949.07 

1185.74 

.0585 

24 

237.75 

239.02 

947.42 

1186.45 

.0610 

25 

240.00 

241.31 

945.82 

1187.13 

.0634 

26 

242.17 

243.52 

944.27 

1187.80 

.0653 

27 

244.28 

245.67 

942.77 

1188.44 

MS3 

28 

246.32 

247.74 

941.32 

1189.06 

.0707 

29 

248.31 

249.76 

939.90 

1189.67 

.0731 

30 

250.24 

251.73 

938.92 

1190.26 

.0755 

31 

252.12 

253.64 

937.18 

1190.83 

.0779 

32 

253.95 

255.51 

935.88 

1191.39 

.0803 

33 

255.73 

257.32 

934-.  60 

1191.93 

.0827 

34 

257.47 

259.10 

933.36 

1192.  4G 

.0851 

35 

259.17 

260.83 

932.15 

1192,98 

.0875 

36 

260.83 

262.52 

930.96 

1193.49 

.0899 

87 

262.45 

264.18 

929.80 

1193.98 

:0922 

38 

264.04 

265.80 

928.67 

1194.47 

.0946 

39 

265.  5"9 

267.38 

927.56 

1194.94 

.0970 

40 

267.12 

268.93 

926.47 

1195.41 

.0994 

41 

268.61 

270.46 

925.40 

1195.86 

1017 

42 

270.07 

271.95 

924.35 

1196.31 

1041 

43 

271.50 

273.41 

923.33 

1196.74 

1064 

"44 

272.91 

274.85 

922.33 

1.197.17 

.1088 

45 

274.29 

276.26 

921.33 

1197.60 

.1111 

46 

275.65- 

277.65 

920.36 

1198.01 

.1134 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   385 
PROPERTIES  OF  SATURATED  STEAM—  Continued. 


Press- 
ure 
above 
zero. 

Temperature. 

Sensible  Heat 
above 
zero  Fahr. 

Latent  Heat. 

Total  Heat 
above 
zero  Fahr. 

Weight  oi 
One  Cubic 
Fool. 

Lba.per 
sq.  in. 

Fahr.  Deg. 

B.T.U. 

B.T.U. 

B.T.U. 

Lbe. 

47 

276.98 

279.01 

919.40 

1198.42 

.1158 

48 

278.29 

280.35 

918.46 

1198.82 

.1181 

49 

279.58 

281.67 

917.54 

1199.21 

.1204 

50 

280.85 

282.96 

916.63 

1199.60 

.1227 

51 

28^.09 

284.24 

915.73 

1199.98 

.1251 

52 

583.32" 

285.49 

914.85 

1200.35 

.1274 

53 

284.53 

286.73 

912.  9S 

1200.73 

.1297 

54 

285'.  72 

287,95 

913.13 

1201.08 

.1320 

55 

286  89 

289.15 

912.29 

1201.44 

.1343 

56 

288.05 

290.33 

911.46 

1201.79 

.1366 

57 

289.11 

291.50 

910.64 

1202.14 

.1388 

58 

290.31 

292.65 

909.83 

1202.48 

.1411 

59 

291.42 

293.79 

909.03 

1202.82 

.1434 

60 

292.52 

294.91 

908.24 

1203.15 

.1457 

61 

293.59 

296.01 

907.47 

1203.48 

.147D 

294.66 

297.10 

906.70 

1203.81 

.1503 

63 

295.71 

298.18 

905  94 

1204.15 

.1524 

64 

296.75 

299  .-24 

905  20 

1204.44 

.1547 

65 

297.77 

300.30 

904.46 

1204.76 

.1569 

66 

298.78 

301.33 

903.73 

1205.07 

.1593 

€7 

299.78 

302.36 

903.01 

1205.37 

.1614 

€8 

300.77 

303.37 

902.29 

1205.67 

il637 

69 

301.75 

304.88 

901.59 

1205.97 

.1659 

70 

302.71 

305.37 

900.89 

1206,26 

.1681 

71 

303.67 

306.  a-> 

900.21 

1206.56 

.1703 

72 

304.61 

307.32 

899.52 

1206.84 

.1725 

73 

305.55 

308.27 

893.85 

1207.13 

.1748 

74 

306.47 

809.22 

898.18 

1207.41 

.1770 

75 

307.38 

310.16 

897.52 

1207.69 

.1792 

76 

308.29 

311.09 

896.87 

1207.90 

.1814 

77 

309.18 

312.01 

89Q.23 

1208.24 

.1836 

78 

810.06 

312.92 

895.59 

1208.51 

.1857 

79 

310.94 

313.82 

894.95 

1208.77 

.1879 

80 

311.81 

314.71 

894.33 

1209.04 

.1901 

81 

312.67 

315.59 

893.70 

1209.30 

.1923 

82 

313.52 

316.46 

893.09 

1209.56 

.1935' 

83 

314.36 

317.33 

892.48 

1209.82 

.1967 

84 

315.19 

318.  1*9 

891.88 

1210.07 

.1988 

85 

316.02 

319.04 

891.28 

1210.32 

.2010 

86 

316.83 

319.8? 

890.69 

1210.57 

.2033 

87 

317.65 

320.71 

890:10  . 

1210.82 

.2053 

88 

318.45 

321.54 

889.52 

1211.06 

.20T5 

89 

319.24 

322.36 

838.94 

1211.31 

.2097 

90 

320.03 

323.17 

888.37 

1211.55 

.2118 

91 
92 
93 
94 

320.82 
321.59 
322.36 
323.12 

323.98 
324.78 
325.57 
326.35 

887.80 
887.24 
S86.68 
885.13 

1211.79 
1212.02 
1212.26 
1212.49 

.213?. 
.2160 
.2183 
.2204 

95 

323.88 

327.13 

885.53 

1212.72 

.2224 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 
PROPERTIES  OF  SATURATED  STEAM— Continued. 


Press- 
ure 
above 
zero. 

Lbs.per 
$q.  in. 

Temperature. 

Sensible  Heat 
above 
zem  Fahr. 

Latent  Heat. 

Total  Heat 
above 
zero  Fahr. 

Weight  of 
One  Cubic 
Foot. 

Lbs" 

Fahr.  Deg. 

B.T.U. 

B.T.U. 

B.T.U. 

96 

324.63 

327.90 

885.04 

1212.95 

.2245 

97 

325.37 

328.67 

884.50 

1213.18 

.2266 

98 

326.11 

329.43 

$83  97 

1213.40 

.2288 

99 

326.84 

330.18 

883  ."44 

1213.62 

.2309 

100 

327.57 

330.93 

882.91 

1213.84 

.2330 

101 

328.29 

331.67 

882.39 

1214.06 

.2351 

102 

329.00 

332.41 

881.87 

3214.28 

.2371 

103 

329.71 

333.14 

881.35 

1214.50- 

.2392 

104 

330.41 

333.86 

880.84 

1214.71 

.2413" 

105 

331.11 

334.58 

880.34 

1214.92 

.2434 

106 

331.80 

335.30 

879.84 

1215.14 

.2454 

107 

332.49 

336.00 

879.34 

1215.35 

.2475 

108 

333.17 

336.71 

878.84 

1215.55 

.2496 

109 

333.85 

337.41 

878.35 

1215.76 

.2516 

110 

334.52 

838.10 

877.86 

1215.97 

.2537 

111 

335.19 

838.79 

877.37 

1216.17 

.2558 

112 

335.85 

339.47 

876.89 

1216.37 

.2578 

113 

336.51 

340.15 

876.41 

1216.57 

.2599 

114 

337.16 

340.83 

875.94 

1216.77 

.2619 

115 

337.81 

341.50 

875.47 

1216.97 

.2640 

116 

338.45 

342.16 

875.00 

1217.17 

.2661 

117 

339.10 

342.83 

874.53 

1217.36 

,2681. 

118 

339.78 

343.48 

874.07 

1217.56 

.2702 

119 

340.36 

344.14 

873.61 

1217.75 

.2722 

120 

340.99 

344.78 

873.15 

1217.94 

.2742 

121 

341.61 

345.43 

872.70 

1218.13 

.2762 

122 

342.23 

346.07 

872.25 

1218.32 

.2782 

123 

342.85 

346.70 

871.80 

1218.51 

.2802 

1.24 

343.46 

347.34 

871.35 

1218.69 

.2822 

125 

844.07 

347.97 

870.91 

1218.88 

.2842 

126 

344.67 

348.59 

870.47 

1219.06 

.2832 

127 

345.27 

349.21 

870.03 

1219.25 

.2882 

128 

345.87 

349.83 

869.59 

1219.43 

.2902 

129 

346.45 

350.44 

869.16 

1219.61 

.2922 

130 

347.05 

351.05 

868.73 

1219.79 

.2943 

131 

347.64 

351.66 

868.30 

1219.97 

.2961 

132 

348.22 

352.26 

867.88 

1220.15 

.2981 

133 

348.80 

352.86 

867.46 

1220.33 

.3001 

134 

349.38 

353.46 

867.03 

1220.50 

.3020 

135 

349.95 

354.05 

866.62 

1220.67 

.3040 

136  / 

350.52 

354.64 

866.20 

1220.85 

.3060 

137 

351.08 

355.23 

866.79 

1221.02 

.3079 

138 

351.75 

355.81 

865.38 

1221.19 

.3099 

139 

352.21 

356.39 

864.97 

1221.36 

.3118 

/I40 

352.76 

356.96 

864.56 

1221.53 

.3188 

141 

353.31 

357.54 

864.16 

1221.70 

.3158 

142 

353.86 

358.11 

863.76 

1221.87 

.3178 

143 

854.41 

358.67 

863.36 

1222.03 

.3199 

144 

354.96 

359.24 

862.96 

1222.20 

.3219 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   387 
PROPERTIES  OF  SATURATED  STEAM — Continued. 


Free*- 
ure 
above 
zero 

Temperature. 

Seneible  Heat 
above 
zero  Fahr. 

Latent  Heat. 

Total  Heat 
above 
zero  Fahr. 

Weight  of 
One  Cubic 
.Foot. 

Lbs.pcr 
sq.  in. 

Fahr.  Deg. 

B.T.U. 

B.T.U. 

B.T.U. 

Lbs. 

145 

355.50 

359.80 

862.56 

1222.36 

.3239 

146 

356.03 

360.85 

862.17 

1222.53 

.3259 

iH 

356.57 

860.91 

861.78 

1222.69 

.3279. 

148 

357.10 

861.46 

861.39 

1222.85 

.3299 

149 

357.63 

362.01 

861.00 

12S3.01 

.3319 

150 

358.16 

362.55 

860.62 

1223.18 

.3340 

151 

358.68 

363.10 

860.23 

1223.33 

.3358 

152 

359.  20 

363  64 

859.85 

1223.49 

.3576 

153 

359.72 

364.17 

859.47 

1223.65 

.3394 

154 

360.23 

364.71 

859.10 

1223.81 

.3412 

155 

360.74 

365.24 

858.72 

1223.97 

.3430 

156 

361.26 

365.77 

858.35 

1224.12 

.3448 

157 

361.76 

366.30 

857.98 

1224.28 

.3466 

158 

362.27 

366.82 

857.61 

1224.43 

.3484 

159 

362.77 

367.34 

857.24 

1224.58 

.3502 

160 

363.27 

367.86 

856.87 

1224.74 

.3520 

161 

363.77 

368.38 

856.50 

1224.89 

.3539 

162 

364.27 

368.89 

856.14 

1225.04 

.3558 

163 

364.76 

869.41 

855.78 

1225.19 

.3577 

164 

365.25 

369.92 

855.42 

1225.34 

.3596 

165 

865.74 

37042 

855.06 

1225.49 

.3614 

166 

366.23 

370.93 

854.70 

1225.64 

.3633 

167 

366.71 

371.43 

854.35 

1225.78 

.3652 

158 

367.19 

371.93 

853.99 

1225.93 

.3671 

169 

367.68 

372.43 

853.64 

1226.08 

.3690 

170 

368.13 

372.93 

853.29 

1226.22 

.3709 

171 

368.63 

373.43 

852.94 

1226.37 

.3727 

172 

369.10 

373.91 

852.59 

1226.51 

.3745 

173 

369.57 

374.40 

852.25 

1226.66 

.3763 

174 

370.04 

374.89 

851.90 

1226.80 

.3781 

175 

370.51 

375.38 

851.56 

1226.94 

.3799 

176 

370.97 

375.86 

851.22 

1227.08 

.3817 

177 

371.44 

376.34 

850.88 

1227.23 

.3835 

173 

371.90 

-376.  82 

850.54 

1227.37 

.3853 

179 

372.36 

$77.30 

850.20 

1227.51      • 

.3871 

m 

372.82 

377.78 

£49.86 

1227.65 

.3889 

181 

373.27 

378.25 

849.53 

1227.78 

.3907 

1S2 

373.73 

378.72 

849.20 

1227.92 

.3925; 

183 

374.18 

379.19 

848.86 

1228.06' 

.3944^ 

184 

374.63 

379.66 

848-.  53 

1228.20 

.3962 

iar> 

375.08 

380.13 

848.20 

1228.33 

.3980 

1S6 

375.52 

380.59 

847.88 

1228.47 

.3999 

187 

375.97 

381.05 

847.55 

1223.61 

.4017 

188 

376.41 

381.51 

847.22 

1228.74 

.4035 

189 

376  85 

381.97 

846.90 

1228.87 

.4053 

190 

377.29 

382.42 

846.58 

1229.01 

.4072 

191 

377.72 

382.88 

846.26 

1229.14 

.4089 

192 

378.16 

383.33 

845.94 

1229.27 

.4107 

193 

378.59 

383.  r<8 

845.62 

1S29.41 

.4125 

388  APPENDIX   CONTAINING   REFERENCES  AND    TABLES. 
PROPERTIES  OF  SATURATED  STEAM — Continued. 


Pressure 
above 
Zero. 

Temperature. 

Sensible  Heat 
above  Zero 
Fahr. 

Latent  Heat. 

Total  Heat 
above  Zero 
Fahr. 

Weight  of 
One  Cubic 
Foot, 

Lbs.  per 
sq.  in. 

Fahr.  Deg. 

B.T.U. 

B.T.U. 

B.T.U. 

Lbs. 

194 

379.02 

384.23 

845.30 

1229.54 

.4143 

195 

379.45 

384.67 

844.99 

1229.67 

.4160 

196 

379.97 

385.12 

844.68 

12:29.80 

.4178 

197 

380.30 

385.56 

844.36 

1229.93 

.4196 

198 

380.72 

386.00 

844.05 

1230.06 

.4214 

199 

381.15 

386.44 

843.74 

1230.19 

.4231 

200 

381.57 

386.88 

843.43 

1230.31 

.4249 

201 

381  99 

387.32 

843.12 

1230.44 

.4266 

202 

382.41 

387.76 

842.81 

K'30.57 

.4283 

203 

382.82 

388.19 

842.50 

1230.70 

.4300 

204 

383.24 

388.62 

842.20 

1230.82 

.4318 

205 

383.65 

389.05 

841.89 

J  230.  95 

.4335 

206 

384  06 

389.48 

841.59 

1*81.07 

.4352 

207 

384.47 

389.91 

841.29 

1231.20 

.4369 

208 

384.88 

390.33 

840.99 

itti.  ae 

.4386 

209 

385.28 

390.75 

840.69 

1231.45 

.4403 

210 

385.67 

391.17 

840.39 

1231.57 

.4421 

QUANTITIES    OF   HEAT   CONTAINED   IN   ONE   POUND    OF   WATER   AT   VARIOUS 
TEMPERATURES,    RECKONED   FROM   ZERO,    FAHRENHEIT. 

[From  Charles  T.  Porter's  treatise  on  The  Richards'  Steam-Engine  Indicator.} 


Tempera- 
ture. 

Heat  con- 
tained above 
Zero. 

Tempera- 
ture. 

Heat  con- 
tained above 
Zero. 

Tempera- 
ture. 

Heat  con- 
tained above 
Zero. 

Fahr.  Deg. 

B.T.U. 

Fahr.  Deg. 

B.T.U. 

Fahr.  Deg. 

B.T.U. 

35 

35.00 

155 

155.33 

275 

276.98 

40 

40.00 

160 

160.37 

280 

282.09 

45 

45.00 

165 

165.41 

285 

287.21 

50 

50.00 

170 

170.45 

290 

292.32 

55 

55.00 

175 

175.49 

295 

297.45 

60 

60.00 

180 

180.54 

300 

302.58 

65 

65.01 

185 

185.59 

305 

307.71 

70 

70.02 

190 

190.64 

310 

312.84 

75 

75.02 

195 

195.69 

315 

317.98 

80 

80.08 

200 

200.75 

320 

323.13 

85 

85.04 

205 

205.81 

325 

328.28 

90 

90.05 

210 

210.87 

330 

333.43 

95 

95.06 

215 

215.93 

335 

338.59 

100 

100.08 

220 

221  .00 

340 

343.75 

105 

105.09 

225 

226.07 

345 

348.92 

110 

110.11 

230 

231.15 

350 

354.10 

115 

115.12 

235 

236.23 

355 

359.28 

120 

120.14 

240 

241.31 

360 

364.46 

125 

125.16 

245 

246.39 

365 

369.65 

130 

130.19 

250 

251.48 

370 

374.84 

135 

135.21 

255 

256.57 

375 

380.04 

140 

140.24 

260 

261.67 

380 

385.24 

145 

145.27 

265 

266.77 

385 

390.45 

150 

150.30 

270 

271.87 

390 

395.67 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   389 


TABLB  No.  XII. 

COMPOSITION  OF  VARIOUS    FUELS  OF  THE  UNITED  STATES. 


C. 

H.      0. 

N. 

s. 

Mois- 
ture. 

Ash. 

Spec. 
Grav. 

78.6 
8s-  8 

2-5     i-7 

0.8 

o-4 

1.2 

148 

i  45 

\% 

1.40 
i-33 

1  32 
1.30 
1.24 

Rhode  Island          "          

10.5 

Massachusetts        "          

92  o 
83  i 

6.0 
7-8 

North  Carolina       "                  .... 

9-i 

Welsh                      *' 

Maryland  Semi-bituminous  

80.5 

75-8 
59-4 
70.0 
52.0 
62.6 
58.2 
59-5 
48.4 
71.0 

4527 

20.2 
38.8 
28.0 
39-0 

35-5 

P:5 

48.8 
17.0 

n 

1.2 

*-7 

8-3 

4.0 

1.8 

2.0 

1.9 

1.30 

*4       (Block)  Bituminous  
Illinois  and  Indiana  (Cannel)  Bituminous 
Kentucky  (Cannel)  Bituminous 

39 

2.8 
12.0 

1.27 

1-25 

i-45 

Tennessee  Bituminous  

Alabama            " 

4i.5 

56.5 

42   6 

2-5 

18  6 

California  and  Oregon  Lignite 

50.1 

0.9 

i-5 

16.7 

13.2 

i-3* 

3-9  13-7 

STATE. 

COAL. 

KIND  OF  COAL. 

Per  Cent,  of 
Ash. 

THEORETICAL  VALUE. 

In  Heat 

Units. 

In  Pounds 
of  Water 
Evaporated. 

Pennsylvania 

44 
44 
M 
44 
44 

Kentucky 

Anthracite 

3-49 
6.13 
2.90 
15.02 
6.50 
10.77 
5.00 
5-60 
9-50 
2.75 

2.00 
14-80 
7.00 

5-20 

5.60 
5-50 
2.50 

5.66 

6.00 

«3-98 
S-oo 
9.25 
4-50 
4.50 

3-40 

i4,i<39 
13,535 
14,221 
i3,*43 
13,368 
13.155 
14,021 
14,265 
ia,324 
H,39i 
15,198 
13,360 
9,326 
1  3.  02  5 
13,123 
12,659 
13,588 
14,146 
13,097 
12,226 
9,215 
'3,562 
13,866 
12,962 
«,55i 
20,746 

14.70 
14.  ot 
14-72 
13.60 
13.84 
13.62 
'451 
14.76 
12-75 
14.89 
16.76 
13.84 
9.65 
13-48 
13  58 
13.10 

14.64 
13-56 
12.65 
9-54 
14.04 
14-35 
13-41 
11.96 
21-47 

H 

Cannel                  .. 

.  .   .      Semi-bituminous  

.                Stone's  Gas      

Youfirhiojrheny. 

Brown  
Caking  

«t 

Cannel  

44 

Illinois 

.  .  Bureau  County  

44 

,        Mercer  County  

44 

Indiana  

M 

Block  
Caking  

Arkansas 

Colorado    .  . 

44 

Texas 

M 

V'aahington. 
Pennsylvania 

44 

Petroleum 

3QO  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 

TABLE   No.    XI L— Continued. 

DRY  ANTHRACITE  COAL— AVERAGE  TABLE  OF  RESULTS.* 


Mine. 

Locality. 

Volatile  Matter. 

4 

Fixed  Carbon. 

z 

O 
£ 
I* 

(A 

u  x 

O.  u 

£ 

'CT3 
3  C_- 
^  3  rt 

|£S 

u      rt 

g|l 

°^So' 

Jfils 

,J 

L.  V.  Buckwheat  

W.-Barre,  Pa.  .  . 
Unknown 

6.21 

6.8 

15-5 

76.94 
80.2 

i-3 

11,959 

12.38 

it                                   14 

5 

14 

81 

1  1,  800 

D    L.  &  W  

M 

84 

Jermyn  Stove  
Woodward 

Schuy.  Co..  Pa... 

6.08 

4   06 

1  1.  02 

82.90 

81  87 

T-425 

12,316 

13-05 

84  38 

Mt    Pleasant  •. 

ti          o 

10.78 

gj  59 

12  A-8 

L.  V.  Pea  
Forty-foot      

L.  V.  region  
Scranton,  Pa 

7-49 

16.23 

76  28 

8U    02 

-52 

11,920 

12-37 

Manville  Shaft    .     .  . 

7    ^3 

86  =; 

It                        H 

r     7g 

5-78 

6ie 

Avondale  
Oxford 

Avondale,  Pa  

6  49 

6.QI 

87.78 

•44 

I3,2l8 

I3-7I 

Mammoth(Buckwh't)  -j 

Dnfton,  Pa.         / 
(Slate  removed)  f 
Cross  Creek.Pa  j_ 

2.44 

6.97 

90-59 

1-55 
i   c;6 

r3,72o 

14.20 

(Slate  removed)  ) 

BITUMINOUS  COAL— AVERAGE  TABLE  OF  RESULTS.-' 


«3 

d 

I 

I* 

%      rt 

-«cjj 

rt 

| 

0 

2*O 

?  -"2 

ws'^  s 

Mine. 

Locality. 

« 

6 

o 

'CTJ 

^  o  rf 

^J^CJ 

-  — 

•o 

i  3  T5 

O  9"  g     • 

C  Q  ^  O 

V 

.  >  o  w 

*o 

| 

X 

o/~ 

So^u 

u 

< 

fa 

* 

K 

^ 

£ 

Gillespie  '. 

Gillespie   111 

36.26 

12.33 

5*  *4* 

1.26 

IO,GO2 

11.28 

o  ^6 

Auburn  Screenings. 

Sugar  Creek,  111  

37.5 

15.2 

47-3 

11,200 

ii.  6 

VJ.^U 

LittlePittsburg,Va. 

Morgantown,  W.  Va. 

37-5 

6.6 

55«9 

I2,8OO 

^3*3 

Bernmont  

Monongahela  R..  Pa. 

32 

8.04 

jo  *y 

59-96 

'•275 

1  3,424 

13-9 

1.04 

Antrim 

New  Blossburg,  Pa.. 

18.54 

II  .30 

70.  16 

1.42 

13,695 

14  18 

0.27 

Eureka  . 

Cleartield  Co.,  Pa     . 

23-79 

:? 

5-82 

7°-39 

1.32 

o,vyo 
J3,897 

°-43 

Turtle  Creek  

Monongahela  R.,  Pa. 

34-95 

4-33 

60.72 

1.28 

I4,45° 

14.96 

0.30 

Nova  Scotia  
Reynoldsville  
Leisenring 

No.  2  Slope,  U.  S 
Reynoldsville,  Pa  
Connellsville.  Pa.  .  .  . 

32-38 
24.67 
29.26 

4.11 

5-37 
6.25 

63-61 
69.96 
64.49 

1  -34 

15,285 

15.86 
15-67 
15.82 

0.27 

o-33 
0.92 

Pocahontas  

New  River,  Va  

17.84 

3-72 

78.45 

*o  *->•*• 
15.82 

0.2 

Cooperstown  

Nova  Scotia  

30-75 

4.09 

65-16 

!-345 

15,435 

15.98 

0-5 

*  From  experiments  made  by  Flory  and  Gilbert  at  Sibley  College,  Cornell 
University.  The  heat-units  are  given  per  pound  of  dry  coal.  Coal  in  ordi- 
nary conditions  contains  from  3  to  10  per  cent  of  moisture,  and  the  results  must 
be  reduced  accordingly.  Seventy  per  cent  of  the  theoretical  heating  value 
represents  the  average  results  obtained  in  practice. 


APPENDIX  CONTAINING  REFERENCES  AND  TABLES.  39 1 

TABLE  No>  XIl.— Continued. 

ANALYSES  OF  ASH. 


Specific 
Grav. 

Color 
of  Ash. 

Silica. 

Alum- 
itia. 

Oxide 

Iron. 

Lime. 

M»p. 

nesia. 

Loss. 

Acids 

S.&P. 

Pennsylvania  Anthracite  
Bituminous  

•559 
•372 

Reddish 
Buff. 
Gray. 

45-6 
76.0 

42-75 

21.00 

44  8 

9-43 
2.60 

1.41 

0-33 
trace 

0.48 
0.40 

Scotch  Bituminous  

z 

37-6 

52.0 

3-7 

i.i 

*  oa 

.27 

IQ.7 

n.  6 

5.8 

23.7 

2.6 

«.8 

TABLE  No.  XIII. 

FOR    REDUCING    BAROMETRIC   OBSERVATIONS  TO  THE 
FREEZING-POINT. 


Reading  of  Ba- 
rometer. 

Correction  at 
10°  Fahr. 

Correction  at 
40°  Fahr. 

Correction  at 
70°  Fahr. 

Correction  at 
90°  Fahr. 

Inches. 

Inches. 

Inches. 

Inches. 

Inches. 

27 

0.045 

O.O28 

0.100 

0.148 

27-5 

0.046 

0.028 

O.  IO2 

O.I5I 

28.0 

0.047 

0.029 

0.104 

0.153 

28.5 

0.048 

0.029 

0.106 

0.156 

29 

0.049 

o  030 

0.108 

0.159 

29-5 

0.050 

0.030 

0.109 

0.162 

30.0 

0.051 

0.031 

O.  Ill 

0.164 

30-5 

0.052 

0.032 

0.113 

0.167 

31-0 

0.053 

0.032 

0.115 

0.170 

392    APPENDIX  CONTAINING  REFERENCES  AND    TABLES. 

TABLE  No.  XIV. 

THERMAL   CONDUCTIVITIES. 

PER   DEGREE    DIFFERENCE   OF   THE    SUBSTANCE. 


Substances. 

Thickness, 
one  metre. 
Calories  per 
sq.  metre. 

Thickness, 
one  foot. 
B.  T.  U.  per 
sq.  ft.  per  hr. 

Authority. 

•?26 

594 

57.5 

104 

Zinc             

56 

1  02 

Lead    

28 

50.5 

Air,                         ] 
Oxygen, 

Nitrogen, 
Carbonic    oxide,  J 

u.ui/y 
0.0137 

«*j*j 

0.0249 

ing  to  kinetic  theory. 
Do.           do.           do. 

O.OI25 

0.0227 

Do.           do.           do. 

Glass                

O.82 

1.40 

Peclet. 

Porphyritic  trachyte  

2.12 

3.86 

Aryton  &   Perry,  Phil.  Mag., 

Marble          

•J.I-7 

5.67 

1878,  first  half  year,  p.  241. 
Peclet. 

Underground  strata.  ..... 

1.8 
1.82 

3-29 
3.31 

Forbes  and  Wm.  Thomson. 

Sandstone  of  Craig-  } 
leith  Quarry            f  '  ' 
Trap-rock  of  Calton  Hill.. 
Sand  of  experimen-  ) 
tal  garden               \  '  ' 
Water  

3-84 
1-5 
0.94 
0.72 

7.0 

2-73 
1.72 

1.82 

Do.          do.          do. 

Do.           do.           do. 
Do.           do.           do. 
J.  P.  Bottomley. 

Fir  across  fibres        . 

o  ocn 

o  169 

P6clet  in  Everett's  Units  and 

"   along  fibres  

O.I  60 

o  308 

Physical  Constants. 
Do.           do            do. 

W^alnut  across  fibres 

o  105 

o  192 

Do            do            do 

"        along  fibres.  .  .  .  . 

O  173 

O  71  C 

Do            do            do 

O  212 

o  ^87 

Do.           do.           do. 

Cork  .. 

O.  IOC, 

O   IQ2 

Do.           do.           do. 

Hempen  cloth    nevv       .  .  . 

o  052 

O  OQ1^ 

Do            do            do 

"      old  

o  043 

o  078 

Do            do            do 

Writing  paper,  white  
Gray  paper  unsized     .... 

0.043 
O.O337 

0.078 
O  O^I^ 

Do.           do.           do. 
Do           do            do 

Calico,  new,  of  ) 

all  densities     f 
Wool,  carded,  of  ) 
all  densities        f  '  ' 
Finely  carded  cotton-wool 
Eider-down  

0.044 

0.04 

O  O3Q 

0.08 

0.073 

0017 

Do.           do.           do. 

Do.          do.           do. 
Do           do           do 

Indian  rubber  

O  17 

o  308 

Brick  dust.  .            .  . 

OT  C 

O  272 

o  06 

o  109 

Coke  

406 

9OI 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES.   393, 


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394  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 

TABLE   No.  XVI. 

WEIGHT    OF    WATER    PER    CUBIC     FOOT    FOR    VARIOUS    TEM- 
PERATURES.* 

WEIGHT  OF  WATER  PER  CUBIC   FOOT,  FROM   32°   TO    212°   F.,  AND   HEAT- 
UNITS  PER  POUND,  RECKONED  ABOVE  32°  F. 


oT 
3 

5  a 

•JS 

,  3 

1 

c 

, 

^,3 

J 

51 

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w 

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ttj     . 

£«  >•)  .»J 

3 

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DC 

H" 

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DC 

H*" 

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X 

H*" 

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X 

32 

62.42 

o. 

78 

62.25 

46.03 

123 

61.68 

91.16 

1  68 

60.8! 

136.44 

33 

62.42 

I. 

79 

62.24 

47-03 

124 

61.67 

92.17 

169 

60.79 

J37-45 

34 

62.42 

2. 

80 

62.23 

48.04 

i25 

61.65 

93-17 

170 

60.77 

138.45 

35 

62.42 

3- 

81 

62  .22 

49.04 

126 

61.63 

94.17 

171 

60.75 

139.46 

36 

62.42 

4. 

82 

62.21 

50.04 

127 

61.61 

95.18 

172 

60.73 

140.47 

37 

62.42 

5. 

83 

62.2O 

51.04 

128 

61.60 

96.18 

173 

60.70 

141.48 

38 

62.42 

6. 

84 

62.  ly 

52.04 

129 

61.58 

97.19 

60.68 

142.49 

39 

62.42 

7- 

85 

62.18 

53-05 

130 

61.56 

98.19 

175 

60.66 

I43-5° 

4° 

62.42 

8. 

86 

62.17 

54-05 

6i.54 

99.20 

176 

60.64 

41 

62.42 

9- 

87 

62.16 

55-05 

132 

61  .52 

IOO.  2O 

177 

60.62 

I45-52 

42 

62.42 

10. 

88 

62.  15 

56-05 

i33 

61.51 

IOI.  21 

178 

60.59 

146.52 

43 

62.42 

ii. 

89 

62.  14 

57-05 

J34 

61.49 

IO2.2I 

179 

60.57 

M7-53 

44 

62.42 

12. 

90 

62.13 

58.06 

61.47 

103.22 

1  80 

60.55 

148.54 

45 

62.42 

Z3' 

91 

62.  12 

59-06 

136 

61.45 

IO4.22 

181 

60.53 

J49-55 

46 

62.42 

14. 

92 

62.11 

60.06 

137 

6i.43 

105  .  23 

182 

60.50 

150-56 

47 

62.42 

T5- 

93 

62.  10 

61.06 

138 

61.41 

106.2^ 

183 

60.48 

J5!  57 

48 

62.41 

16. 

94 

62.09 

62.06 

61.39 

107.24 

184 

60.46 

49 

62.41 

I7- 

95 

62.08 

63.07 

140 

61.37 

108.25 

185 

60.44 

T53-59 

5° 

62.41 

18. 

96 

62.07 

64.07 

141 

61.36 

109  25 

186 

60.41 

154.60 

Sl 

52 

62.41 
62.40 

19. 
20. 

97 
98 

62.06 
62.05 

65.07 
66.07 

142 

6i-34 
61.32 

110.26 
111.26 

187 
1  88 

60.39 
60.37 

JSS-^i 
156.62 

53 

62.40 

21  .OI 

99 

62.03 

67.08 

144 

61.30 

112.27 

189 

60.34 

I57-63 

54 

62.40 

22.01 

ioo 

62.02 

68.08 

145 

61.28 

113.28 

190 

60.32 

158.64 

55 

62.39 

23.0 

ioi 

62.OI 

69.08 

146 

61.26 

114.28 

191 

60.29 

159-65 

56 

62.39 

24.0 

102 

62.00 

70.09 

i47 

61.24 

115.29 

192 

60.27 

160.67 

57 

62.39 

25.0 

I03 

61.99 

71.09 

148 

6l  .22 

116.29 

193 

60.25 

161.68 

58 

62.38 

26.O 

I04 

61.97 

72.09 

149 

61.20 

117.30 

194 

60.22 

162.69 

g 

62.38 
62.37 

27.0 
28.0 

106 

61.96 
61.95 

73-10 
74.10 

61.18 
61.16 

118.31 

119.31 

196 

6O.2O 
60.17 

163  .70 
164.71 

•61 

62.37 

29.01 

107 

61.93 

75.10 

I52 

61.14 

120.32 

197 

60.15 

165.72 

62 

62.36 

3O.OI 

108 

6l.92 

76.  10 

r53 

61.12 

121  -33 

198 

60.  12 

166.73 

63 

62.36 

31.01 

109 

61.91 

77-ii 

154 

61.10 

122.33 

199 

60.  10 

167.74 

64 

62.35 

32.OI 

no 

61.  89 

78.11 

61.08 

I23-34 

200 

60.07 

168.75 

62.34 

33-01 

in 

61.88 

79.11 

ip 

61.04 

124-35 

201 

60.05 

169.77 

-66 

62.34 

34-02 

112 

61.86 

80.12 

61.06 

I25-35 

202 

6o.02 

170.78 

67 

62  -33 

35-02 

"3 

61.85 

81.12 

158 

61  .02 

126.36 

203 

6o.OO 

171.79 

68 

62.33 

36   02 

114 

61.83 

82.13 

61.00 

127.37 

204 

59-97 

172.80 

69 

62.32 

37-02 

115 

61.82 

83-13 

160 

60.98 

128.37 

205 

59-95 

173.81 

70 

62.31 

38.02 

116 

61.80 

84.13 

161 

60.96 

129.38 

206 

59-92 

174-83 

71 

62.31 

39-02 

117 

61.78 

85.14 

162 

60.94 

J3°-39 

207 

59-89 

I75-84 

72 

62.30 

40.02 

118 

61.77 

86.14 

163 

60.92 

131.40 

208 

59-87 

176.85 

73 

62.29 

41.02 

119 

61.75 

87.15 

164 

60.90 

132.41 

209 

59-84 

177.86 

74 

62.28 

42.03 

1  20 

61.74 

88.  15 

165 

60.87 

T33-4i 

2IO 

59-82 

178.87 

75 

62.28 

43-03 

121 

61.72 

89-15 

166 

60.85 

134.42 

211 

59  79 

179.89 

70 

62.27 

44-03 

123 

61  .70 

90.16 

167 

60.83 

212 

59-76 

180.90 

77 

62.26 

45-°3 

WEIGHT  OF  WATER  AT  TEMPERATURES  ABOVE  212°  F. 

Porter  (Richards'  "  Steam-engine  Indicator,11  p.  52)  says  that  nothing  is  known  about  the 
expansion  of  water  above  212°  F.  Applying  formulae  derived  from  experiments  made  at  tem- 
peratures below  212°  F.,  however,  the  weight  and  volume  above  212°  F.  may  be  calculated, 
but  in  the  absence  of  experimental  data  we  are  not  certain  that  the  formulae  hold  good  at 
higher  temperatures. 


*  Kent's  "  Pocket-book  for  Mechanical  Engineers.'1 


APPENDIX  CONTAINING  REFERENCES  AND  TABLES.    395 


TABLE  No.  XVI.— Continued. 

Thurston,  in  his  "  Engine  and  Boiler  Trials,"  gives  a  table  from  which  we  take  the  follow- 
ing (neglecting  the  third  decimal  place  given  by  him): 


-§£ 

.  3 

3| 

rt     b 

•°.% 

& 

.  3 

rt      fe 

*4i 

•J.5 

,3 

H,u  si 

-ffcj 

||| 

||| 

O.J.T  ti 

.fjjj 

HI 

|&£ 

£«*, 

8*5 

Ssi 

flj   ^  [rt 

H 

£ 

H 

* 

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^ 

H 

£ 

H 

^ 

212 

59-71 

280 

57-90 

3|o 

55-52 

420 

52.86 

490 

50.03 

220 

59-64 

290 

57.59 

360 

55.16 

430 

52.47 

500 

49.61 

230 

59-37 

300 

57.26 

370 

54-79 

440 

52.07 

5«o 

49  .20 

240 

T 
260 

59.10 
58.81 
58-52 

310 
320 
330 

56.93 
56.58 
56-24 

380 
39° 
400 

54-41 
54-03 
53-64 

450 
46o 

51.06 
51.26 

50.85 

520 
530 
540- 

48.78 
48.36 

47-94 

270 

58.21 

340 

55-88 

410 

53.26 

48o 

50.44 

550 

47.52 

Box  on  Heat  gives  the  following: 

Temperature  F 212°          250°  300°  350°          400° 

Lbs.  per  cubic  foot 59.82        58.85  57.42  55.94        54.34 

TABLE  No.  XVII. 


450° 
52.70 


500- 
51.02 


600° 
47.64 


PRESSURE    OF    WATER    PER    SQUARE     INCH     FOR     DIFFERENT 
HEIGHTS    IN    FEET.* 

At  60°  F.  i  foot  head  =  0.433  Ib.  per  square  inch,  .433  X  144  =  62.352  Ibs.  per  cubic  foot. 


Head, 
Feet. 

o 

I 

2 

3 

4 

5 

6 

7 

8 

9 

0 

0-433 

0.866 

1.299 

i  732 

2.165 

2.508 

3.031 

3.434 

3.897 

10 

4-33° 

4-763 

5-196 

5.629 

6.062    6.495 

6.928 

7-361 

7-794 

8.227 

20 

8.660 

9-093 

9.526 

9-959 

10.392 

10.825 

11.258 

ii  .691 

12.  124 

12-557 

30 

40 

12.990 
17.320 

13-423 
I7-753 

13.856 
18.186 

14.289 
18.619 

14.722 
19-052 

I5-155 
19-485 

15.588 
19.918 

16.021 
20.351 

'6.454 
20.784 

16.887 

21  .217 

50 

21  .650 

22.083 

22.516 

22.949 

23.382 

23.815 

24.248 

24.681 

25.114 

25.547 

60 

25.980 

26.413 

26.846 

27.279 

27.712 

28.145 

28.578 

29.011 

29-444 

29.877 

70 

^0.310 

30.743 

31.176 

31  609 

32  042   32.475 

32.908 

33-341 

33-774 

34-207 

80 
90 

34.640 
38.970 

35-073 
39-403 

35.506 
39-836 

35-9>9 
40.269 

36.372 
40.702 

36.805 
4i-i35 

37-238 
•41-568 

37-67I 
42.001 

38.104 
42.436 

38.537 
42.867 

HEAD    IN    FEET    OF    WATER,    CORRESPONDING   TO    PRESSURES 
IN    POUNDS    PER   SQUARE    INCH. 

i  lb.  per  square  inch  =  2.30947  feet  head,  i  atmosphere  -  14-7  Ibs.  per  square  inch  =  33.95 

feet  head. 


Press- 
ure. 

0 

t 

2 

3 

4 

5 

6 

7 

8 

9 

| 

o 
10 

20 

3° 
40 
SO 

23.0947 
46.189* 

69  2841 
115.4735 

2.309 
25.404 
48.499 
71-594 
94.688 
117.78 

4.619 

50!  808 
73-903 
96.998 
I2O.O9 

6.928 
30.023 
53  "8 
76.213 
99.307 
122.40 

9.238 
32-333 
55-427 
78.522 
101.62 
124.71 

"•547 
34-642 
57-737 
80  831 

IC3-93 
126.02 

13-857 
36-952 
60.046 
83.14- 
106.24 
129.33 

16.166 
^9.261 
62.356 
?S  450 
108.55 
131.64 

18.476 
41.570 
64.665 
87-760 
110.85 
'33-95 

20.785 
43.880 
66.975 
90.069 
113.16 
136.26 

60 

70 

138.5682:140  88 
161  .6620  163.97 

143.19   'HS.SO 
166.28    168.59 

147.81 
170.90 

150.12   152.42 

T54-73 
177-83 

180.14 

J59-35 
182.45 

80 

184.7576 

187.07 

189.38 

191.69 

194.00 

196.31 

198.61 

200.92 

203.23  1205.54 

90 

207.8523 

210.16 

212-47 

214.78 

217.09 

219.40 

221.71 

224.02 

226.33 

228.04 

*  Kent's  "  Pocket-book." 


396  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 

TABLE   No.  XVIII. 

CONTENTS    IN   CUBIC    FEET   AND   U.    S.    GALLONS    OF   PIPES 

AND   CYLINDERS   OF   VARIOUS   DIAMETERS   AND 

i    FOOT   IN    LENGTH.* 

i  gallon  =  231  cubic  inches,     i  cubic  foot  =  7.4805  gallons. 


Diamtter  in 
Inches. 

For  i  Foot  in 
Length. 

Diameter  in 
Inches. 

For  i  Foot  in 
Length. 

Diameter  in 
Inches. 

For  i  Foot  in 
Length. 

Cu.  Ft  , 
also  Area 
in  Sq.  Ft. 

U.S. 
Gals..  231 
Cu.  In. 

Cu.  Ft., 
also  Area 
in  Sq.  Ft. 

U.  S. 
Gals..  231 
Cu.  In. 

Cu.  Ft., 
also  Area 
in  Sq.  Ft. 

U.  S. 

Gals.,  231 
Cu.  In. 

A 

.0003 
.0005 

.0025 
.004 

6% 
7 

.2485          1.859 
.2673         1.999 

%H 

1.960 
2.074 

H-73 

i 

.0008 

.0057 

7*4 

.2867 

2.145 

20 

2.18-; 

16.32 

A 

.001 

.0078 

7*18 

•  3068 

2.295 

20^ 

2  .292 

T 

.0014 

.0102 

7H 

•3276 

2-45 

21 

2.405 

17.99 

t 

.0017 

.0021 

.0129 

8 

•3491 
-3712 

2.611 

2-777 

21*13 

22 

2.521 
2.640 

18.86 
J9-75 

A 

.OO26 

.0193 

8*£ 

•3941 

2.948 

22*£ 

2.761 

20.66 

i 

.0031 

.0230 

8^4 

•  4-76 

3-I25 

23 

2.885 

21.58 

H 

.0036 

.0269 

9 

.4418 

3-305 

23*6 

3.012 

22-53 

I 

.0042 

.0312 

9*4 

•  4667 

3-491 

24 

3.I42 

23.50 

& 

.0048 

'°°55 

-0359 
.0408 

9% 

.4922 
•5185 

3.682 
3-879 

25 
26 

3.409 
3.687 

25-50 
27-58 

^ 

.0085 
.0123 

.0638 
.0918 

10 

10*4 

•5454 
•5730 

4.08 
4.286 

27 

28 

4.276 

29.74 
31-99 

i% 

.0167 

.1249 

Io*4 

.6013 

4.498 

29 

4.587 

34-31 

2 

.0218 

.1632 

Io94 

.6303          4.715 

3° 

4.909 

36.72 

2*4 

.0276 

.2066 

ii 

•66         !     4.937 

31 

5.241 

39-2t 

2>4 

.0341 

.2550 

"*4 

-6903 

5.164 

32 

41.78 

2% 

.0412 

•3085 

nj| 

.7213 

5-396 

33 

5-940 

44-43 

3 

.0491 

.3672 

"94 

-7530 

5  633 

34 

6.305 

47.16 

.0576 

.4309 

12 

-7854 

5-875 

35 

6.681 

49.98 

.ji2 

.0668 

-4998 

I2*12 

.8522 

6-375 

36 

7.069 

52.88 

3*4 

.0767 

•5738 

13 

.9218 

6.895 

37 

7.467 

55-86 

4 

.0873 

•  6528 

•994 

7-436 

38 

7.876 

58.92 

4*4 

•0985 

•7369 

14 

.069 

7-997 

39 

8.296 

62.06 

4*£ 

•  II34 

.8263 

I?** 

.147 

8.578 

40 

8.727 

65.28 

5 

•  1231 
.1364 

.9206 

(.O2O 

.227 
.3:0 

0.180 
9.801 

41 
42 

9.168 
9.621 

68.58 
7'  97 

•1503 

'.I25 

16 

•396 

10.44 

43 

10.085 

75-44 

5*£ 

•  1650 

•234 

1  6*4 

.485 

ii  .  ii 

44 

10-559 

78.99 

sM 

.1803 

•349 

17 

.576 

11.79 

45 

11.045 

82.62 

6 

.1963 

•469 

i7)4 

.670 

12.49 

46 

11.541 

86-33 

6*4 

.2131 

•594 

18 

.768 

13.22 

47 

12.048 

90.13 

6*1 

•2304 

•7*4 

18* 

.867 

13.96 

48 

12.566 

94.00 

To  find  the  capacity  of  pipes  greater  than  the  largest  given  in  the  table  look  in  the  table 
for  a  pipe  of  one  half  the  given  size,  and  multiply  its  capacity  by  4;  or  one  of  one  third  its 
size,  and  multiply  its  capacity  by  9,  etc. 

To  find  the  weight  of  water  in  any  of  the  given  sizes  multiply  the  capacity  in  cubic  feet  by 
62*4  or  the  gallons  by  8^6,  or,  if  a  closer  approximation  is  required,  by  the  weight  of  a  cubic 
foot  of  water  at  the  actual  temperature  in  the  pipe. 

Given  the  dimensions  of  a  cylinder  in  inches  to  find  its  capacity  in  U.  S.  gallons :  square 
the  diameter,  multiply  by  the  length  and  by  .0034.  If  d  =  diam.  /  =  length,  gallons  = 


*  Kent's  "  Pocket-book. 


APPENDIX  CONTAINING  REFERENCES  AND   TABLES.  397 

TABLE  No.  XIX. 

EQUALIZATION    OF    PIPE   AREAS.* 


Sizes 
of  Pipe. 

r-.h 
%" 

%:" 

3*4    " 

4^     " 
5 
6 

7 
8         " 

Nu-'ber  of  small  pipes  required  to  make  area  equivalent  to  one  larger  pipe,  with 
allowance  for  friction. 

& 

% 

in. 

I 

in. 

«H 

in. 

?K 

in. 

2 

in. 

*X 

in. 

3 
in. 

& 
in. 

4 

in. 

& 
in. 

5 
in. 

6 
in. 

7 
in. 

8 
in. 

..!. 

2.O 

3-7 
1.8 

i 

7.6 
3-7 

2.0 

i 

"•3 
5-4 
3-i 
i-5 

1 

19 

9-2 

1.1 

8., 

9-3 
4-5 

55 
25-5 
14-7 
7-3 

80 
39 

2 

i   .6 

108 
53 
30 
•4-7 
9.8 
5-8 
3-5 
2-4 
1.4 
i 

146 
70 
39 
19-5 
»3-4 
7.8 
4-7 

2-7 

1.8 
1  3 

i 

1  88 
90 
53 

3.. 

9-9 

5-9 
3-5 

290 

•£ 

$ 

16 
9-3 

5-4 

427 

210 
117 

g 

23 
»3-7 

$ 

595 
295 
»65 
80 
54 
32 
19 
ii 

i 

x.83 

i 

2.Q 

*-7 

-5 
•5 

1.7 

1.25 

2.7 

2 

1.6 

4-i 
3-3 
2-5 

i-5 

i 

5-5 
4.1 
3-2 

2 

1/4 

i 



*  Especially  computed. 


398  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 

TABLE  No.  XX. 

TEMPERATURES   OF   VARIOUS   LOCALITIES. 

COMPILED  FROM  OBSERVATIONS  OF  THE  SIGNAL  SERVICE,  U.  S.  A.,  AND 
BLODGETT'S  "CLIMATOLOGY  OF  THE  UNITED  STATES." 

NOTE.— In  the  United  States  the  comfortable  temperature  of  the  air  in  occupied  rooms  is 
generally  70  degrees  when  walls  have  the  same  temperature. 


Station. 

No.  of 
months  fire 
s  required. 

Mean  temp, 
of   cold 
months. 

Av.  No.  ofj 
deg.  temp, 
to  be  raised. 

Max.  No. 
deg.  temp, 
to  be  raised. 

Minimum 
tempera- 
ture F°. 

Albany    NY         . 

1 

3^ 

3" 

87 

—  17 

Baltimore,  Md  
Boston,  Mass  
Buffalo   NY 

6 

8 

39 
37 

qc 

3i 

3^ 

qc, 

72 
8l 

8? 

—     2 
—  II 
—  iq 

Burlington   Vt     

7 

q2 

38 

qo 

—  2O 

Chicago    111       

7 

35 

3^ 

9° 

—  20 

Charleston,  S.  C  
Cincinnati    O  

3 

7 

52 
42 

18 

2^ 

47 

77 

+  23 

—    7 

Cleveland    O 

7 

18 

§3 

—  iq 

Detroit   Mich        .... 

7 

qc 

q^ 

QO 

—  2O 

Duluth   Minn             .  . 

8 

28 

4- 

ioS 

—  38 

Indianapolis,  Ind  
Key  West,  Fla  
Leavenworth,  Kan  

7 

0 

6 

6 

41 
O 

37 
42 

2o 

o 

33 
28 

88 
26 
90 
80 

-  18 

+  44 

—  20 
—    IO 

Memphis,  Tenn  
Milwaukee  Wis     .  .  .. 

8 

39 

^7 

3' 

q  5 

68 

QC 

+     2 
—  25 

New  Orleans,  La  
New  York,  N.  Y  
Philadelphia,  Pa  

0 

7 

7 
7 

o 
40 
40 

30 

i  ) 
30 

3" 
qr 

44 
76 

75 
82 

+  26 

—    6 

-    5 

—   12 

Portland    Me 

8 

qq 

q7 

82 

—   12 

Portland    Ore         

6 

4"3 

2" 

67 

4-     3 

San  Francisco,  Cal.  ...... 
St.  Louis,  Mo  

4 
c 

53 

•57 

I? 

33 

34 
86 

+  36 

—  16 

St    Paul    Minn 

7 

2^ 

4c, 

IO2 

—  32 

Washington,  D.  C  
Wilmington    N    C 

5 

40 

CQ 

3" 
20 

73 

CC 

+    3 

4-  1^ 

APPENDIX  CONTAINING  REFERENCES  AND  TABLES,    399 


:  :  :  :  :888885,88 
:  :  :  :  :*$SnW$3S 


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400  APPENDIX  CONTAINING  REFERENCES  AND  TABLES. 

TABLE   XXI. — Continued. 

PRICE-LIST   OF    PIPE,    ADOPTED    JAN.  29,   1895. 


Diameter,  inches  

\& 

H 

% 

^ 

% 

jl/f 

Butt-weld,  black  

.Each 

$005$ 

$0.05$ 

$o.o5i 

$0.07 

$0.08^ 

$0.1  if 

$0  iqi 

41           galvanized. 

08 

•°7$ 

,07$ 

ooi 

-ni 

16 

Diameter,  inches  

tH 

2 

2^ 

3 

3tf 

4 

4^ 

5 

6 

Lap-  weld,  black                        Each 

$0  26 

So  ^ 

So   =J2 

So  68 

40  81 

Si  2c; 

Si  42 

$i  8^ 

galvanized  '" 

62 

80 

08 

i  16 

For  selected  pipe,  or  pipe  cut  to  specified  lengths,  the  discount  will  be  five 
(5)  per  cent  less  in  the  gross  (i.e.,  5  per  cent  higher  in  gross  list  discount)  than 
on  regular  pipe. 

On  pipe  lighter  than  standards,  or  without  threads  or  sockets,  no  extra 
allowance  will  be  made. 


INDEX 


A 

PAGE 

Absolute  pressure,  defined 120 

zero 6 

Air,  analysis  of 27 

,  change  of,  in  a  room 51 

delivered  in  pipes,  table ; 286 

,  discharge,  different  temperatures,  table  of 45 

,  discharge,  different  pressures 42 

,  flues,  indirect  heating 232 

,  force  required  for  moving 35 

,  humidity  of 29 

,  inlet,  location  of 46 

,  measurement  of  velocity 37 

,  microbe  organisms  in , 23 

,  properties  of,  table 381 

,  relation  between  velocity  and  force,  table 45 

required  for  ventilation 31,  202 

-supply  for  furnace 272 

-trap 1 80 

-valves 102 

,  velocity  of,  how  computed 39 

,  weight  of 22 

Anemometer,  description  of 37 

Angle-valves 100 

Area  of  main  pipe 192 

of  pipes,  hot-water  heating 229 

of  safety-valve 1 50 

of  steam-pipes 222,  226 

of  ventilating-flues ., 52 

Areas  and  circumferences  of  circles 376 

Argon 27 

Atmosphere,  composition  and  pressure  of 21 

B 

Bacteria  in  air 23 

Bailey,  L.  H.,  tests.... 245 

Barometer 21 

Blower,  capacity  of 292 

401 


402  INDEX. 

VA.GE 

Blow-off  cocks  and  valves. 157 

Boiler  explosions 172 

Boiler  horse-power,  standard  established 122 

Boiler-setting,  depth  of  foundation  for „ . .  . 145 

Boiler,  size  of,  hot-blast  heating,  practical  construction 292-4 

Boiler  specifications 326 

Boilers,  appliances  for 147 

,  brick  settings  for 143 

,  fire-tube 128 

,  heating,  classes  of 1 30 

,  forms  of 129 

,  for  soft  coal 142 

,  setting  of 147 

,  horizontal  tubular 130 

,  locomotive  and  marine 131 

,  portable  settings  for 147 

,  power 128 

,  sectional 140 

,  steam-heating,  care  of 169 

,  steam,  requisites  of 127 

,  tubular 138 

,  types  of 128 

,  water-tube 133,  138 

Boiling-points,  gases 9 

Books,  list  of,  on  heating 353 

Bourdon  pressure-gauge 154 

Branch  tees 97 

Breeching 145 

Brick  settings  for  boilers 143 

Bucket  traps 165 

Buildings,  loss  of  heat  from 54 

C 

Calorie,  defined .  „ . . 4 

Capacity  of  boiler 122 

Capital  invested  in  manufacture 2 

Carbonic  acid,  CO2 ,  or  carbon  dioxide 24 

Carbonic  oxide,  CO 26 

Ceiling  and  floor  plates 98 

Check-valves 102 

Chimneys,  form  of -. 160 

,  size  of 161 

Chimney-tops 162 

Coal,  soft,  kind  of  heater  for 142 

Cocks  and  valves 98 

Cocks,  blow-off 157 

,  try 152 


INDEX.  403 

PAGE 

Combination  heaters : 188 

Conduction  of  heat 188 

Connection  to  radiators  in  hot-water  heating  systems 195 

Contents  of  pipe  in  gallons 396 

Convected  heat 60 

Convection      iq 

,  formula  for 63 

Cooling  of  rooms 300 

Couplings,  right  and  left 93 

,  union 93 

Coverings  for  pipes 198 

D 

Damper-regulators - 156 

Dead-weight  safety-valve 149 

Density  and  weight  per  cubic  foot  of  water 394 

Diagram  of  heat  from  radiating  surfaces 204 

Diathermancy,  denned 16 

Diffusion,  amount  of 35 

of  gases 24 

of  radiant  heat 17 

Dimensions  of  steam,  gas,  and  water  pipe,  table 399 

Direct  and  indirect  heating 60 

Drip-pipes 228 

Drop  tubes  for  boilers. ...   139 


E 

Elbows  and  bends 94 

Electrical  and  heat  equivalents 301 

heaters 306 

heating 301 

expense 303 

units,  value  of 5 

Equalization  of  pipe-areas,  use  of  table .  .  - 286 

table  for  air 287 

for  steam 397 

Equalizing  valve  i63 

Exhaust-steam  heating 247 

,  table  of  dimensions 249 

Expansion  of  pipes 260 

Expansion-joints 106 

-tank 158 

-traps * 166 

Explosions,  boiler  172 

Explosions  of  hot- water  heaters   1 76 

Extended-surface  heaters 139 


404  INDEX. 

F 

PAGE 

Factory  and  workshop  heating 245 

Fans  and  blowers 289 

Field  tube 1 39 

Fittings,  miscellaneous 96 

pipe 92 

Flange-union,  joint 94 

Float  traps , 165 

Flues,  dimensions  of  52 

for  forced-blast  system 284 

,  indirect  heating,  table 233 

,  ventilation,  size  of 49 

Forced-blast  systems  of  heating 283 

Foot-pound,  defined 3 

Foundation,  depth  of,  for  boiler-setting  145 

Fuels  of  the  United  States,  table . .  . . : 389 

Furnace,  form  of 270 

,  heating,  formula  for  dimensions 274 

,  proportions  of 272 

Furnaces,  directions  for  operating 118 

G 

Gases  and  air,  flow  of 40 

,  diffusion  of 24 

Gate-valve 100 

Gauge-pressure 153 

Gauges,  Bourdon 1 54 

,  U-shaped,  water 38 

,  vacuum 155 

Globe  valve 99 

Governor  for  pump 255 

Grates,  kind  of 163 

Gravity  circulating  system 178 

Green-house  heating ,  236 

H 

Heat,  bodily  sensation  of jg 

,  conduction  of 1 8 

,  demand  for i 

,  flow  through  metals .  61 

,  latent 15,  121 

\  loss  of,  from  buildings . .  54 

,  measurement  of,  in  test 71 

,  mechanical  equivalent   . .    3 

,  nature  of 2 

,  radiant 15,  61 


INDEX.  405 

PACK 

Heat,  radiant,  diffusion  of ij 

,  transmitted,  table  of ij 

,  relation  to  electricity  and  work 2 

removed  by  convection ijt  53 

required  for  ventilation 58 

,  specific 14 

supplied  by  radiating  surfaces ....  60 

,  total,  emitted  from  radiating  surfaces,  diagram 203 

transformation 4 

transmission,  table  of 69 

,  test  of 264 

-unit '4- 

Heaters,  extended  surface  136 

,  hot- water 135 

,  care  of 171 

,  explosions  of 1 76 

,  setting  of 148 

,  indirect,  setting  of 1 18 

Heating-boilers,  classification  of 130 

,  for  soft  coal 142 

,  setting  of 147 

with  magazines 141 

Heating,  indirect,  amount  of  surface  required  for 209 

-surfaces,  indirect,  tests  of 79 

,  systems  of 20 

,  with  fan 283 

H igh-pressure  system 178,  254 

Hot  air  and  steam,  combination  of 190 

heating 268 

formula  for 273 

Hot-blast  heating,  radiating  surface  required 291 

system,  air  heated 293 

,  heating  surface 293 

,  size  of  blower   294 

Hot-water  and  steam  heating,  tests 242^ 

heaters 135 

,  care  of 171 

,  explosions  of 176 

,  setting  of 148 

heating,  general  table,  proportions 237 

,  rule  for  pipes 232 

,  table  of  data 229 

of  pipes 231 

radiators 112 

Howard  regulator 3J6 

Humidity  of  air 29,  363 

Hygrometer,  description  of 29 


406  INDEX. 

I 

PAGR 

Indirect  heating,  air-flues 232 

,  dimensions  of  registers 235 

,  factors  for  flues 234 

,  surface  required,  table  for 84 

,  table  of  proportions 238 

,  tests  of  surfaces 79 

radiators 116 

,  efficiency  of 84 

,  experiments  on 81 

Industry,  magnitude  of i 

Insulating  substance,  best  known 198 


J 

Johnson  system  of  heat  regulation 318 

Joint,  lead,  how  formed 87 

,  rust,  how  made 88 

Joints,  flange-union. 94 


L 

Lap-welding,  process  of 89 

Latent  heat 15 

Lawler  regulator 312 

Lead  joint,  how  formed 87 

Leader-pipe , 276 

Lever  safety-valve 149 

Literature  and  references 353 

Logarithms,  how  to  use 357 

of  numbers,  table  of 377 

Loss  in  transmitting  steam 260 


M 

Main  pipes,  exhaust-steam 249 

,  hot- water  heating 231 

,  steam-heating  table 226 

,  steam  and  hot-water 237 

Manometer 153 

Marine  boilers 132 

Mason  reducing  valve 260 

Maynard  (S.  T.)  greenhouse  test 242 

Melting-points,  table  of 12 

Mill's  experiments  on  steam-heated  surfaces 77 

system  of  piping 181 


INDEX.  4O7 

N 

PAGE 

Nipples,  hooks,  etc  97 

Nitrogen 27 

O 

Oxygen 25 

Ozone 25 

P 

Papers  devoted  to  heating 355 

Paul  system • 254 

Pettersson's  apparatus  for  determining  CO2 28 

Petticoat-pipe 131 

Pipe-boilers 138 

-connections,  hot- water  heating  systems 193 

,  steam-heating  systems ........   191 

-fittings 92 

,  radiating  surface  of 107 

,  return ....  1 79 

,  steel 91 

Pipe  systems,  comparisons  of 197 

,  table  of  dimensions 399 

,  wrought-iron 89 

,  thickness  and  size  of 89 

Pipes,  method  of  computing  area .  222 

Piping  for  indirect  heaters 196 

,  method  of,  in  greenhouses 239 

,  in  hot- water  heating ,    .  185 

,  systems  of 180 

Pitch,  defined 179 

Pilot's  tube,  description  of 38 

Plain-surface  boilers   136 

Plates,  ceiling  and  floor 98 

Pop-valve 150 

Portable  setting  for  boilers 147 

Power's  regulator 3*3 

Pressure-gauge . 153 

,  Bourdon 154 

Pressure,  methods  of  measuring 153 

systems  of  hot- water  heating 159 

Properties  of  air,  table  of  ... 381 

of  steam,  table  of 384 

Proportions,  hot-air  heating 275 

Protection  of  main  pipe  from  lose  of  heat 197 

of  pipes ^6 1 

Pump-governor -  -  255 

Strength  of  materials,  table 379 


408  INDEX. 

PAGE 

Pyrometers 1 1 

,  calorimetric 12 

R 

Radiint  heat,  defined 60 

,  diffusion  of . .    17 

,  emissive  power,  table  of , 16 

,  transmission  of 17 

Radiating  surface,  exhaust-steam  heating 249 

for  greenhouses 241 

,  hot-blast  heating. 291 

,  measurement  of 73 

of  pipe 107 

,  proportioning  of 201 

,  results  of  tests. 75 

,  rules  for 215 

surfaces,  effect  of  painting 74 

Radiation 15 

,  amount  of f 61 

,  direct , 60 

,  indirect 60 

Radiators,  contents  of,  how  determined 74 

,  direct  indirect 1 16 

,  effect  of  grouping  surfaces 67 

,  extended  surface 79 

,  flue   112 

,  heat  from 60 

,  hot-water , 112 

,  testing 72 

,  indirect 116 

,  efficiency  of 84 

,  experiments  on 81 

,  material  of 67 

,  method  of  testing 69 

,  proportion  of  parts  of 119 

.sectional no 

,  tests 78-83 

,  valves 101 

,  vertical-pipe 109 

Reducing-valves « 258 

Reflection  and  transmission  of  radiant  heat 16 

power,  table  of 16 

Refrigerating  machines,  heating  with 299 

Registers,  area  of,  hot-air  heating 274 

,  dimensions  of 52,  235 

for  forced-blast  system   , 200 

,  table  of 280 

,  table  of  dimensions 275 


INDEX. 


409 


Regulator  for  temperature  .......  v.  .....................................  P^* 

Regulators,  damper  ..........  .....................................  I56 

Relations  of  units  for  measuring  pressures  .........................  !  ee 

Relay,  term  denned  ................................................  ,7 

Relief-  or  drip-pipe  ..................................................  I7 

Reliefs  .................................   .........................  22g 

Return  pipes  ........................................  ,  ...............  ljg 

>  lableV'  ...............................................    227 

steam-traps  ..................................................  j^ 

Risers  ..............................................................  r  -9 

Rules,  approximate,  for  estimating  radiating  surface  .....................  215 

,  hot-water  mains  .............................................  232 

,  steam-mains   ............  ,  .....................................  224 

Rust-joint,  how  made  ...........  ..  .....................................  88 

S 
Safety-valve  ........................................................    149 

,  area  of  ..................................................   150 

Setting  of  heating-boilers  ..............................    ..............   147 

of  hot-  water  heaters  ...........................................   148 

of  indirect  heaters  ............................................   118 

Settings,  brick,  for  boilers  .............................................    143 

Single-pipe  system  for  hot-water  heating.  .-.  .............................   188 

Siphon,  term  defined  ..................................................   179 

-trap  .....................................  ....................    !64 

Specific  heat  ............................   .............................     14 

Specifications,  heating  apparatus  .......................................   322 

,  tubular  boiler  ...........................................   34  1 

Stacks,  table  for  .....................................................   278 

Standard  forms,  hot  water  and  steam  specifications  .......................   323 

Steam  and  water,  flow  of  ..............................................   217 

,  circulation,  comparisons  of  ...........................     82 

Steam-boiler,  requisites  of  ..........................................  121-127 

-fitter's  tools  ....................................................   349 

-heating,  general  table  of  proportions  ...  ..........................  237 

-loop  .............................  .  .............................  257 

radiators,  cast-iron  ............................................   no 

,  vertical-pipe  ..........................................    109 

tables,  explanation  of  ...........................................    120 

-thermometer  ...................................................     13 

transmission   ......  .  ...........................................   260 

-traps  ....................................   ..................  164,  180 

Steel  pipe  .....................................................   ......     91 

T 

Tables,  see  list  on  page  ................................................   35° 

Taft,  L.  R  ,  tests  ....................    ...........................  .....   244 


4IO  INDEX. 

PAGE 

Tank,  expansion 158 

Tees,  Y's,  pipe-junction,  etc 95 

Temperature,  boiling,  table  of 22 

in  various  localities  of  the  United  States,  table 398 

,  melting-points 12 

,  measured  by  color  . .    12 

produced  by  given  amount  of  surface 85 

regulators 310 

,  saving  due  to 320 

required i 

Test  of  loss  in  steam-transmission =  —  265 

Thermal  conductivity,  table  of 392 

Thermometer,  air  and  mercurial 10 

-cup 13 

,  Fahrenheit  and  centigrade 7 

,  maxima  and  minima 12 

,  steam 13,  1 56 

,  use  of ....  13 

Thermostat..  .  t 310 

Tools,  steam-fitter's 349 

Transmission  of  steam 260 

Traps,  bucket 165 

,  counterweighted , 165 

,  expansion 166 

,  float   165 

,  gravitating- return 169 

,  siphon 164 

,  steam 164-180 

,  steam-return 167 

Tredgold's  experiments,  summary  of 76 

Try-cocks t 152 

Tubular  boilers 138 

,  horizontal 130 

,  specifications  for 341 

Two-pipe  system  of  steam-heating 184 

Types  of  boilers 128 


U 

Underground  pipe  systems 261 

Unit  of  heat 4 


V 

Vacuum- gauges  155 

Valves,  air 102 

,  angle 100 

,  check   .....  .  102 


INDEX.  41 1 

PAGE 

Valves,  corner  and  cross .' 101 

,  equalizing 168 

,  gate loo 

,  globe 99 

,  pop 150 

,  position  of,  in  pipes 195 

,  radiator , 101 

,  safety 149 

Velocity  of  air  due  to  heat 43 

of  water  and  steam 219 

of  water,  hot- water  heating 220 

Ventilation,  air  required 31 

by  heat 35 

by  suction 42 

ducts 269 

-flues,  size  of 49 

,  table  of 238 

,  influence  of  size  of  room , 34 

inlet  for  air 44 

,  mechanical 36 

,  principles  of , 21 

,  relation  to  heating 21 

space  for  each  person 52 

,  summary  of  problems 50 

,  systems  of 298 

Vertical  boilers 132 


W 

Warming,  systems  of 20 

Water  and  steam  circulation,  comparison  of 82 

,  flow  of 217 

Water-columns 153 

-hammer .  .   . .   180 

-surface,  steam  and  water  space 126 

-tube  boilers 133,  138 

Watts 5 

Welding-lap,  process  of 89 

Willame's  system 253 

Windows,  loss  of  heat  from 54 

Wolff's  rule  for  steam-  mains 225 

Workshop  and  factory  heating 245 

Wrought-iron  pipe •  •  •  •  • 89 


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MAR  II  1822 


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